From 080ebc087ec50fd16e3a01d9529109f2bedbb222 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 22 May 2026 14:54:21 +0000
Subject: [PATCH 1/6] Initial plan


From 64da99fb4aac0f11d091fe098a19c2ab9f024066 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 22 May 2026 15:07:00 +0000
Subject: [PATCH 2/6] Add LINQ FirstOrDefault support wrappers for NS
 collection generics

Agent-Logs-Url: https://github.com/dotnet/macios/sessions/04597ed5-86b1-4feb-b522-8990c6006023

Co-authored-by: rolfbjarne <249268+rolfbjarne@users.noreply.github.com>
---
 src/Foundation/NSCollectionLinqExtensions.cs  | 85 +++++++++++++++++++
 src/frameworks.sources                        |  1 +
 tests/monotouch-test/Foundation/ArrayTest.cs  |  9 ++
 .../Foundation/NSMutableArray1Test.cs         |  9 ++
 tests/monotouch-test/Foundation/NSSet1Test.cs |  9 ++
 5 files changed, 113 insertions(+)
 create mode 100644 src/Foundation/NSCollectionLinqExtensions.cs

diff --git a/src/Foundation/NSCollectionLinqExtensions.cs b/src/Foundation/NSCollectionLinqExtensions.cs
new file mode 100644
index 000000000000..c9365fcd0647
--- /dev/null
+++ b/src/Foundation/NSCollectionLinqExtensions.cs
@@ -0,0 +1,85 @@
+using System.Collections.Generic;
+
+#nullable enable
+
+namespace System.Linq {
+	public static class NSCollectionLinqExtensions {
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		public static TValue? FirstOrDefault<TValue> (this Foundation.NSMutableArray<TValue> source) where TValue : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.FirstOrDefault ((IEnumerable<TValue>) source);
+		}
+
+		public static TValue? FirstOrDefault<TValue> (this Foundation.NSMutableArray<TValue> source, Func<TValue, bool> predicate) where TValue : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.FirstOrDefault ((IEnumerable<TValue>) source, predicate);
+		}
+
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+	}
+}
diff --git a/src/frameworks.sources b/src/frameworks.sources
index accf45f75e36..4ea1cd028503 100644
--- a/src/frameworks.sources
+++ b/src/frameworks.sources
@@ -852,6 +852,7 @@ FOUNDATION_SOURCES = \
 	Foundation/NSOrderedCollectionDifference.cs \
 	Foundation/NSOrderedCollectionDifference_1.cs \
 	Foundation/NSConnection.cs \
+	Foundation/NSCollectionLinqExtensions.cs \
 	Foundation/NSData.cs \
 	Foundation/NSDate.cs \
 	Foundation/NSDictionary.cs \
diff --git a/tests/monotouch-test/Foundation/ArrayTest.cs b/tests/monotouch-test/Foundation/ArrayTest.cs
index 8965e909538c..10cc12004972 100644
--- a/tests/monotouch-test/Foundation/ArrayTest.cs
+++ b/tests/monotouch-test/Foundation/ArrayTest.cs
@@ -199,5 +199,14 @@ public void Enumerator ()
 				Assert.That (list [0].ToString (), Is.EqualTo ("abc"), "Value");
 			}
 		}
+
+		[Test]
+		public void LinqFirstOrDefault_MutableArray ()
+		{
+			using var array = new NSMutableArray ();
+			array.Add ((NSString) "abc");
+			var first = array.FirstOrDefault ();
+			Assert.That (first, Is.EqualTo ((NSString) "abc"), "FirstOrDefault");
+		}
 	}
 }
diff --git a/tests/monotouch-test/Foundation/NSMutableArray1Test.cs b/tests/monotouch-test/Foundation/NSMutableArray1Test.cs
index c5189f2b0944..63ada4fc6ce8 100644
--- a/tests/monotouch-test/Foundation/NSMutableArray1Test.cs
+++ b/tests/monotouch-test/Foundation/NSMutableArray1Test.cs
@@ -1,4 +1,5 @@
 using System.Collections;
+using System.Linq;
 
 namespace MonoTouchFixtures.Foundation {
 
@@ -238,5 +239,13 @@ public void IEnumerable1Test_EnumeratorType ()
 				Console.WriteLine (item.LongValue);
 			}
 		}
+
+		[Test]
+		public void LinqFirstOrDefaultTest ()
+		{
+			using var arr = new NSMutableArray<NSString> ((NSString) "1", (NSString) "2");
+			var first = arr.FirstOrDefault ();
+			Assert.That (first, Is.EqualTo ((NSString) "1"), "FirstOrDefault");
+		}
 	}
 }
diff --git a/tests/monotouch-test/Foundation/NSSet1Test.cs b/tests/monotouch-test/Foundation/NSSet1Test.cs
index 782309ea9224..6e049a3f35d3 100644
--- a/tests/monotouch-test/Foundation/NSSet1Test.cs
+++ b/tests/monotouch-test/Foundation/NSSet1Test.cs
@@ -294,6 +294,15 @@ public void IEnumerable1Test_EnumeratorType ()
 			}
 		}
 
+		[Test]
+		public void LinqFirstOrDefaultTest ()
+		{
+			using var st = new NSSet<NSString> ((NSString) "1", (NSString) "2");
+			var first = st.FirstOrDefault ();
+			Assert.That (first, Is.Not.Null, "FirstOrDefault");
+			Assert.That (st.Contains (first), Is.True, "Contains");
+		}
+
 		[Test]
 		public void IEnumerableTest ()
 		{

From c40d8390b2cd6c5e97e5126ad0cc7c0e632ccdde Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 22 May 2026 15:07:37 +0000
Subject: [PATCH 3/6] Align generic type naming in NS collection LINQ
 extensions

Agent-Logs-Url: https://github.com/dotnet/macios/sessions/04597ed5-86b1-4feb-b522-8990c6006023

Co-authored-by: rolfbjarne <249268+rolfbjarne@users.noreply.github.com>
---
 src/Foundation/NSCollectionLinqExtensions.cs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/Foundation/NSCollectionLinqExtensions.cs b/src/Foundation/NSCollectionLinqExtensions.cs
index c9365fcd0647..6b106908b93f 100644
--- a/src/Foundation/NSCollectionLinqExtensions.cs
+++ b/src/Foundation/NSCollectionLinqExtensions.cs
@@ -43,17 +43,17 @@ public static class NSCollectionLinqExtensions {
 			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source, predicate);
 		}
 
-		public static TValue? FirstOrDefault<TValue> (this Foundation.NSMutableArray<TValue> source) where TValue : class, Foundation.INativeObject
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
-			return Enumerable.FirstOrDefault ((IEnumerable<TValue>) source);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
 		}
 
-		public static TValue? FirstOrDefault<TValue> (this Foundation.NSMutableArray<TValue> source, Func<TValue, bool> predicate) where TValue : class, Foundation.INativeObject
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
-			return Enumerable.FirstOrDefault ((IEnumerable<TValue>) source, predicate);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source, predicate);
 		}
 
 		public static TKey? FirstOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject

From 21dd1baa923d6aa07fc64c898edd67cbc3c55751 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Mon, 25 May 2026 11:50:19 +0000
Subject: [PATCH 4/6] Add all LINQ method overloads with XML docs and tests for
 all 6 NS generic collections

Agent-Logs-Url: https://github.com/dotnet/macios/sessions/64b2c1cf-9d19-4995-a591-9392aad2cfc5

Co-authored-by: rolfbjarne <249268+rolfbjarne@users.noreply.github.com>
---
 src/Foundation/NSCollectionLinqExtensions.cs  | 2840 ++++++++++++++++-
 .../Foundation/NSCollectionLinqTest.cs        | 1521 +++++++++
 2 files changed, 4345 insertions(+), 16 deletions(-)
 create mode 100644 tests/monotouch-test/Foundation/NSCollectionLinqTest.cs

diff --git a/src/Foundation/NSCollectionLinqExtensions.cs b/src/Foundation/NSCollectionLinqExtensions.cs
index 6b106908b93f..fa636d2ae0a0 100644
--- a/src/Foundation/NSCollectionLinqExtensions.cs
+++ b/src/Foundation/NSCollectionLinqExtensions.cs
@@ -4,12 +4,50 @@
 
 namespace System.Linq {
 	public static class NSCollectionLinqExtensions {
+		// NSSet<TKey>
+		/// <summary>Returns the first element of <see cref="Foundation.NSSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The first element in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey First<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.First ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the first element of <see cref="Foundation.NSSet{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey First<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.First ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the first element of <see cref="Foundation.NSSet{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The first element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		public static TKey? FirstOrDefault<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
 		}
 
+		/// <summary>Returns the first element of <see cref="Foundation.NSSet{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		public static TKey? FirstOrDefault<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
@@ -17,12 +55,480 @@ public static class NSCollectionLinqExtensions {
 			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source, predicate);
 		}
 
+		/// <summary>Returns the last element of <see cref="Foundation.NSSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The last element in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey Last<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Last ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSSet{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey Last<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Last ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSSet{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The last element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSSet{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The single element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty or contains more than one element.</exception>
+		public static TKey Single<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Single ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSSet{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element or more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey Single<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Single ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSSet{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The single element of <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> contains more than one element.</exception>
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSSet{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the element at a specified index in <see cref="Foundation.NSSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="index">The zero-based index of the element to retrieve.</param>
+		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="index"/> is less than 0 or greater than or equal to the number of elements in <paramref name="source"/>.</exception>
+		public static TKey ElementAt<TKey> (this Foundation.NSSet<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ElementAt ((IEnumerable<TKey>) source, index);
+		}
+
+		/// <summary>Returns the element at a specified index in <see cref="Foundation.NSSet{TKey}"/>, or <see langword="null"/> if the index is out of range.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="index">The zero-based index of the element to retrieve.</param>
+		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>, or <see langword="null"/> if the index is out of range.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSSet<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ElementAtOrDefault ((IEnumerable<TKey>) source, index);
+		}
+
+		/// <summary>Determines whether <see cref="Foundation.NSSet{TKey}"/> contains any elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns><see langword="true"/> if <paramref name="source"/> contains any elements; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static bool Any<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Any ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Determines whether any element of <see cref="Foundation.NSSet{TKey}"/> satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns><see langword="true"/> if any element in <paramref name="source"/> passes the test in <paramref name="predicate"/>; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static bool Any<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Any ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Determines whether all elements of <see cref="Foundation.NSSet{TKey}"/> satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns><see langword="true"/> if every element in <paramref name="source"/> passes the test in <paramref name="predicate"/>, or if the collection is empty; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static bool All<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.All ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the number of elements in <see cref="Foundation.NSSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The number of elements in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static int Count<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Count ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the number of elements in <see cref="Foundation.NSSet{TKey}"/> that satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static int Count<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Count ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns a <see cref="long"/> that represents the total number of elements in <see cref="Foundation.NSSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The number of elements in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static long LongCount<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.LongCount ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns a <see cref="long"/> that represents the number of elements in <see cref="Foundation.NSSet{TKey}"/> that satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static long LongCount<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.LongCount ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Filters elements of <see cref="Foundation.NSSet{TKey}"/> based on a predicate.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Where ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Filters elements of <see cref="Foundation.NSSet{TKey}"/> based on a predicate that incorporates each element's index.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element; the second parameter represents the zero-based index of the element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Where ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Projects each element of <see cref="Foundation.NSSet{TKey}"/> into a new form.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TResult">The type of the value returned by <paramref name="selector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="selector">A transform function to apply to each element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSSet<TKey> source, Func<TKey, TResult> selector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (selector);
+			return Enumerable.Select ((IEnumerable<TKey>) source, selector);
+		}
+
+		/// <summary>Projects each element of <see cref="Foundation.NSSet{TKey}"/> into a new form by incorporating each element's index.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TResult">The type of the value returned by <paramref name="selector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="selector">A transform function to apply to each element; the second parameter represents the zero-based index of the element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSSet<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (selector);
+			return Enumerable.Select ((IEnumerable<TKey>) source, selector);
+		}
+
+		/// <summary>Sorts the elements of <see cref="Foundation.NSSet{TKey}"/> in ascending order according to a key.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TOrderKey">The type of the key returned by <paramref name="keySelector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="keySelector">A function to extract a key from an element.</param>
+		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted according to a key.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
+		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (keySelector);
+			return Enumerable.OrderBy ((IEnumerable<TKey>) source, keySelector);
+		}
+
+		/// <summary>Sorts the elements of <see cref="Foundation.NSSet{TKey}"/> in descending order according to a key.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TOrderKey">The type of the key returned by <paramref name="keySelector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="keySelector">A function to extract a key from an element.</param>
+		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted in descending order according to a key.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
+		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (keySelector);
+			return Enumerable.OrderByDescending ((IEnumerable<TKey>) source, keySelector);
+		}
+
+		/// <summary>Bypasses a specified number of elements in <see cref="Foundation.NSSet{TKey}"/> and returns the remaining elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="count">The number of elements to skip before returning the remaining elements.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements after the skipped ones.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSSet<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Skip ((IEnumerable<TKey>) source, count);
+		}
+
+		/// <summary>Bypasses elements in <see cref="Foundation.NSSet{TKey}"/> as long as a condition is true, then returns the remaining elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the elements starting at the first element that does not satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.SkipWhile ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns a specified number of contiguous elements from the start of <see cref="Foundation.NSSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="count">The number of elements to return.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the specified number of elements from the start of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSSet<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Take ((IEnumerable<TKey>) source, count);
+		}
+
+		/// <summary>Returns elements from <see cref="Foundation.NSSet{TKey}"/> as long as a specified condition is true.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> as long as the condition is true.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.TakeWhile ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns distinct elements from <see cref="Foundation.NSSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains distinct elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Distinct ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Inverts the order of the elements in <see cref="Foundation.NSSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements correspond to those of <paramref name="source"/> in reverse order.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Reverse ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Concatenates <see cref="Foundation.NSSet{TKey}"/> with another sequence.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="second">The sequence to concatenate to <paramref name="source"/>.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the concatenated elements of the two sequences.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="second"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSSet<TKey> source, IEnumerable<TKey> second) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (second);
+			return Enumerable.Concat ((IEnumerable<TKey>) source, second);
+		}
+
+		/// <summary>Creates a <see cref="List{T}"/> from <see cref="Foundation.NSSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>A <see cref="List{T}"/> that contains elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static List<TKey> ToList<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ToList ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Creates an array from <see cref="Foundation.NSSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An array that contains elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey [] ToArray<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ToArray ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Applies an accumulator function over <see cref="Foundation.NSSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="func">An accumulator function to be invoked on each element.</param>
+		/// <returns>The final accumulator value.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey Aggregate<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (func);
+			return Enumerable.Aggregate ((IEnumerable<TKey>) source, func);
+		}
+
+		/// <summary>Applies an accumulator function over <see cref="Foundation.NSSet{TKey}"/> with a seed value.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TAccumulate">The type of the accumulator value.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="seed">The initial accumulator value.</param>
+		/// <param name="func">An accumulator function to be invoked on each element.</param>
+		/// <returns>The final accumulator value.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
+		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSSet<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (func);
+			return Enumerable.Aggregate ((IEnumerable<TKey>) source, seed, func);
+		}
+
+		// NSMutableSet<TKey>
+		/// <summary>Returns the first element of <see cref="Foundation.NSMutableSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The first element in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey First<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.First ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the first element of <see cref="Foundation.NSMutableSet{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey First<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.First ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the first element of <see cref="Foundation.NSMutableSet{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The first element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
 		}
 
+		/// <summary>Returns the first element of <see cref="Foundation.NSMutableSet{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
@@ -30,56 +536,2358 @@ public static class NSCollectionLinqExtensions {
 			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source, predicate);
 		}
 
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		/// <summary>Returns the last element of <see cref="Foundation.NSMutableSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The last element in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey Last<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
-			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
+			return Enumerable.Last ((IEnumerable<TKey>) source);
 		}
 
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		/// <summary>Returns the last element of <see cref="Foundation.NSMutableSet{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey Last<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
-			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source, predicate);
+			return Enumerable.Last ((IEnumerable<TKey>) source, predicate);
 		}
 
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		/// <summary>Returns the last element of <see cref="Foundation.NSMutableSet{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The last element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
-			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
+			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source);
 		}
 
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		/// <summary>Returns the last element of <see cref="Foundation.NSMutableSet{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
-			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source, predicate);
+			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source, predicate);
 		}
 
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		/// <summary>Returns the only element of <see cref="Foundation.NSMutableSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The single element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty or contains more than one element.</exception>
+		public static TKey Single<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
-			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
+			return Enumerable.Single ((IEnumerable<TKey>) source);
 		}
 
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		/// <summary>Returns the only element of <see cref="Foundation.NSMutableSet{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element or more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey Single<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
-			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source, predicate);
+			return Enumerable.Single ((IEnumerable<TKey>) source, predicate);
 		}
 
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		/// <summary>Returns the only element of <see cref="Foundation.NSMutableSet{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The single element of <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> contains more than one element.</exception>
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
-			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
+			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source);
 		}
 
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		/// <summary>Returns the only element of <see cref="Foundation.NSMutableSet{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
-			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source, predicate);
+			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the element at a specified index in <see cref="Foundation.NSMutableSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="index">The zero-based index of the element to retrieve.</param>
+		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="index"/> is less than 0 or greater than or equal to the number of elements in <paramref name="source"/>.</exception>
+		public static TKey ElementAt<TKey> (this Foundation.NSMutableSet<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ElementAt ((IEnumerable<TKey>) source, index);
+		}
+
+		/// <summary>Returns the element at a specified index in <see cref="Foundation.NSMutableSet{TKey}"/>, or <see langword="null"/> if the index is out of range.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="index">The zero-based index of the element to retrieve.</param>
+		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>, or <see langword="null"/> if the index is out of range.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ElementAtOrDefault ((IEnumerable<TKey>) source, index);
+		}
+
+		/// <summary>Determines whether <see cref="Foundation.NSMutableSet{TKey}"/> contains any elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns><see langword="true"/> if <paramref name="source"/> contains any elements; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static bool Any<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Any ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Determines whether any element of <see cref="Foundation.NSMutableSet{TKey}"/> satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns><see langword="true"/> if any element in <paramref name="source"/> passes the test in <paramref name="predicate"/>; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static bool Any<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Any ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Determines whether all elements of <see cref="Foundation.NSMutableSet{TKey}"/> satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns><see langword="true"/> if every element in <paramref name="source"/> passes the test in <paramref name="predicate"/>, or if the collection is empty; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static bool All<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.All ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the number of elements in <see cref="Foundation.NSMutableSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The number of elements in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static int Count<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Count ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the number of elements in <see cref="Foundation.NSMutableSet{TKey}"/> that satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static int Count<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Count ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns a <see cref="long"/> that represents the total number of elements in <see cref="Foundation.NSMutableSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The number of elements in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static long LongCount<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.LongCount ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns a <see cref="long"/> that represents the number of elements in <see cref="Foundation.NSMutableSet{TKey}"/> that satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static long LongCount<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.LongCount ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Filters elements of <see cref="Foundation.NSMutableSet{TKey}"/> based on a predicate.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Where ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Filters elements of <see cref="Foundation.NSMutableSet{TKey}"/> based on a predicate that incorporates each element's index.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element; the second parameter represents the zero-based index of the element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Where ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Projects each element of <see cref="Foundation.NSMutableSet{TKey}"/> into a new form.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TResult">The type of the value returned by <paramref name="selector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="selector">A transform function to apply to each element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableSet<TKey> source, Func<TKey, TResult> selector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (selector);
+			return Enumerable.Select ((IEnumerable<TKey>) source, selector);
+		}
+
+		/// <summary>Projects each element of <see cref="Foundation.NSMutableSet{TKey}"/> into a new form by incorporating each element's index.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TResult">The type of the value returned by <paramref name="selector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="selector">A transform function to apply to each element; the second parameter represents the zero-based index of the element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableSet<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (selector);
+			return Enumerable.Select ((IEnumerable<TKey>) source, selector);
+		}
+
+		/// <summary>Sorts the elements of <see cref="Foundation.NSMutableSet{TKey}"/> in ascending order according to a key.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TOrderKey">The type of the key returned by <paramref name="keySelector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="keySelector">A function to extract a key from an element.</param>
+		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted according to a key.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
+		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (keySelector);
+			return Enumerable.OrderBy ((IEnumerable<TKey>) source, keySelector);
+		}
+
+		/// <summary>Sorts the elements of <see cref="Foundation.NSMutableSet{TKey}"/> in descending order according to a key.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TOrderKey">The type of the key returned by <paramref name="keySelector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="keySelector">A function to extract a key from an element.</param>
+		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted in descending order according to a key.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
+		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (keySelector);
+			return Enumerable.OrderByDescending ((IEnumerable<TKey>) source, keySelector);
+		}
+
+		/// <summary>Bypasses a specified number of elements in <see cref="Foundation.NSMutableSet{TKey}"/> and returns the remaining elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="count">The number of elements to skip before returning the remaining elements.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements after the skipped ones.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSMutableSet<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Skip ((IEnumerable<TKey>) source, count);
+		}
+
+		/// <summary>Bypasses elements in <see cref="Foundation.NSMutableSet{TKey}"/> as long as a condition is true, then returns the remaining elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the elements starting at the first element that does not satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.SkipWhile ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns a specified number of contiguous elements from the start of <see cref="Foundation.NSMutableSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="count">The number of elements to return.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the specified number of elements from the start of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSMutableSet<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Take ((IEnumerable<TKey>) source, count);
+		}
+
+		/// <summary>Returns elements from <see cref="Foundation.NSMutableSet{TKey}"/> as long as a specified condition is true.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> as long as the condition is true.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.TakeWhile ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns distinct elements from <see cref="Foundation.NSMutableSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains distinct elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Distinct ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Inverts the order of the elements in <see cref="Foundation.NSMutableSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements correspond to those of <paramref name="source"/> in reverse order.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Reverse ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Concatenates <see cref="Foundation.NSMutableSet{TKey}"/> with another sequence.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="second">The sequence to concatenate to <paramref name="source"/>.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the concatenated elements of the two sequences.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="second"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSMutableSet<TKey> source, IEnumerable<TKey> second) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (second);
+			return Enumerable.Concat ((IEnumerable<TKey>) source, second);
+		}
+
+		/// <summary>Creates a <see cref="List{T}"/> from <see cref="Foundation.NSMutableSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>A <see cref="List{T}"/> that contains elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static List<TKey> ToList<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ToList ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Creates an array from <see cref="Foundation.NSMutableSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An array that contains elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey [] ToArray<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ToArray ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Applies an accumulator function over <see cref="Foundation.NSMutableSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="func">An accumulator function to be invoked on each element.</param>
+		/// <returns>The final accumulator value.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey Aggregate<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (func);
+			return Enumerable.Aggregate ((IEnumerable<TKey>) source, func);
+		}
+
+		/// <summary>Applies an accumulator function over <see cref="Foundation.NSMutableSet{TKey}"/> with a seed value.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TAccumulate">The type of the accumulator value.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="seed">The initial accumulator value.</param>
+		/// <param name="func">An accumulator function to be invoked on each element.</param>
+		/// <returns>The final accumulator value.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
+		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSMutableSet<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (func);
+			return Enumerable.Aggregate ((IEnumerable<TKey>) source, seed, func);
+		}
+
+		// NSArray<TKey>
+		/// <summary>Returns the first element of <see cref="Foundation.NSArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The first element in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey First<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.First ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the first element of <see cref="Foundation.NSArray{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey First<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.First ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the first element of <see cref="Foundation.NSArray{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The first element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the first element of <see cref="Foundation.NSArray{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The last element in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey Last<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Last ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSArray{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey Last<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Last ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSArray{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The last element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSArray{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The single element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty or contains more than one element.</exception>
+		public static TKey Single<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Single ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSArray{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element or more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey Single<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Single ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSArray{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The single element of <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> contains more than one element.</exception>
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSArray{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the element at a specified index in <see cref="Foundation.NSArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="index">The zero-based index of the element to retrieve.</param>
+		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="index"/> is less than 0 or greater than or equal to the number of elements in <paramref name="source"/>.</exception>
+		public static TKey ElementAt<TKey> (this Foundation.NSArray<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ElementAt ((IEnumerable<TKey>) source, index);
+		}
+
+		/// <summary>Returns the element at a specified index in <see cref="Foundation.NSArray{TKey}"/>, or <see langword="null"/> if the index is out of range.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="index">The zero-based index of the element to retrieve.</param>
+		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>, or <see langword="null"/> if the index is out of range.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSArray<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ElementAtOrDefault ((IEnumerable<TKey>) source, index);
+		}
+
+		/// <summary>Determines whether <see cref="Foundation.NSArray{TKey}"/> contains any elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns><see langword="true"/> if <paramref name="source"/> contains any elements; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static bool Any<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Any ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Determines whether any element of <see cref="Foundation.NSArray{TKey}"/> satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns><see langword="true"/> if any element in <paramref name="source"/> passes the test in <paramref name="predicate"/>; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static bool Any<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Any ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Determines whether all elements of <see cref="Foundation.NSArray{TKey}"/> satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns><see langword="true"/> if every element in <paramref name="source"/> passes the test in <paramref name="predicate"/>, or if the collection is empty; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static bool All<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.All ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the number of elements in <see cref="Foundation.NSArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The number of elements in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static int Count<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Count ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the number of elements in <see cref="Foundation.NSArray{TKey}"/> that satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static int Count<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Count ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns a <see cref="long"/> that represents the total number of elements in <see cref="Foundation.NSArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The number of elements in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static long LongCount<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.LongCount ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns a <see cref="long"/> that represents the number of elements in <see cref="Foundation.NSArray{TKey}"/> that satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static long LongCount<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.LongCount ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Filters elements of <see cref="Foundation.NSArray{TKey}"/> based on a predicate.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Where ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Filters elements of <see cref="Foundation.NSArray{TKey}"/> based on a predicate that incorporates each element's index.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element; the second parameter represents the zero-based index of the element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Where ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Projects each element of <see cref="Foundation.NSArray{TKey}"/> into a new form.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TResult">The type of the value returned by <paramref name="selector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="selector">A transform function to apply to each element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSArray<TKey> source, Func<TKey, TResult> selector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (selector);
+			return Enumerable.Select ((IEnumerable<TKey>) source, selector);
+		}
+
+		/// <summary>Projects each element of <see cref="Foundation.NSArray{TKey}"/> into a new form by incorporating each element's index.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TResult">The type of the value returned by <paramref name="selector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="selector">A transform function to apply to each element; the second parameter represents the zero-based index of the element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSArray<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (selector);
+			return Enumerable.Select ((IEnumerable<TKey>) source, selector);
+		}
+
+		/// <summary>Sorts the elements of <see cref="Foundation.NSArray{TKey}"/> in ascending order according to a key.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TOrderKey">The type of the key returned by <paramref name="keySelector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="keySelector">A function to extract a key from an element.</param>
+		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted according to a key.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
+		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSArray<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (keySelector);
+			return Enumerable.OrderBy ((IEnumerable<TKey>) source, keySelector);
+		}
+
+		/// <summary>Sorts the elements of <see cref="Foundation.NSArray{TKey}"/> in descending order according to a key.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TOrderKey">The type of the key returned by <paramref name="keySelector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="keySelector">A function to extract a key from an element.</param>
+		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted in descending order according to a key.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
+		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSArray<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (keySelector);
+			return Enumerable.OrderByDescending ((IEnumerable<TKey>) source, keySelector);
+		}
+
+		/// <summary>Bypasses a specified number of elements in <see cref="Foundation.NSArray{TKey}"/> and returns the remaining elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="count">The number of elements to skip before returning the remaining elements.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements after the skipped ones.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSArray<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Skip ((IEnumerable<TKey>) source, count);
+		}
+
+		/// <summary>Bypasses elements in <see cref="Foundation.NSArray{TKey}"/> as long as a condition is true, then returns the remaining elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the elements starting at the first element that does not satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.SkipWhile ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns a specified number of contiguous elements from the start of <see cref="Foundation.NSArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="count">The number of elements to return.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the specified number of elements from the start of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSArray<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Take ((IEnumerable<TKey>) source, count);
+		}
+
+		/// <summary>Returns elements from <see cref="Foundation.NSArray{TKey}"/> as long as a specified condition is true.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> as long as the condition is true.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.TakeWhile ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns distinct elements from <see cref="Foundation.NSArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains distinct elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Distinct ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Inverts the order of the elements in <see cref="Foundation.NSArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements correspond to those of <paramref name="source"/> in reverse order.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Reverse ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Concatenates <see cref="Foundation.NSArray{TKey}"/> with another sequence.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="second">The sequence to concatenate to <paramref name="source"/>.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the concatenated elements of the two sequences.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="second"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSArray<TKey> source, IEnumerable<TKey> second) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (second);
+			return Enumerable.Concat ((IEnumerable<TKey>) source, second);
+		}
+
+		/// <summary>Creates a <see cref="List{T}"/> from <see cref="Foundation.NSArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>A <see cref="List{T}"/> that contains elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static List<TKey> ToList<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ToList ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Creates an array from <see cref="Foundation.NSArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An array that contains elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey [] ToArray<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ToArray ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Applies an accumulator function over <see cref="Foundation.NSArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="func">An accumulator function to be invoked on each element.</param>
+		/// <returns>The final accumulator value.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey Aggregate<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (func);
+			return Enumerable.Aggregate ((IEnumerable<TKey>) source, func);
+		}
+
+		/// <summary>Applies an accumulator function over <see cref="Foundation.NSArray{TKey}"/> with a seed value.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TAccumulate">The type of the accumulator value.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="seed">The initial accumulator value.</param>
+		/// <param name="func">An accumulator function to be invoked on each element.</param>
+		/// <returns>The final accumulator value.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
+		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSArray<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (func);
+			return Enumerable.Aggregate ((IEnumerable<TKey>) source, seed, func);
+		}
+
+		// NSMutableArray<TKey>
+		/// <summary>Returns the first element of <see cref="Foundation.NSMutableArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The first element in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey First<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.First ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the first element of <see cref="Foundation.NSMutableArray{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey First<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.First ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the first element of <see cref="Foundation.NSMutableArray{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The first element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the first element of <see cref="Foundation.NSMutableArray{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSMutableArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The last element in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey Last<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Last ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSMutableArray{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey Last<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Last ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSMutableArray{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The last element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSMutableArray{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSMutableArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The single element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty or contains more than one element.</exception>
+		public static TKey Single<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Single ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSMutableArray{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element or more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey Single<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Single ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSMutableArray{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The single element of <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> contains more than one element.</exception>
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSMutableArray{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the element at a specified index in <see cref="Foundation.NSMutableArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="index">The zero-based index of the element to retrieve.</param>
+		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="index"/> is less than 0 or greater than or equal to the number of elements in <paramref name="source"/>.</exception>
+		public static TKey ElementAt<TKey> (this Foundation.NSMutableArray<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ElementAt ((IEnumerable<TKey>) source, index);
+		}
+
+		/// <summary>Returns the element at a specified index in <see cref="Foundation.NSMutableArray{TKey}"/>, or <see langword="null"/> if the index is out of range.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="index">The zero-based index of the element to retrieve.</param>
+		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>, or <see langword="null"/> if the index is out of range.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ElementAtOrDefault ((IEnumerable<TKey>) source, index);
+		}
+
+		/// <summary>Determines whether <see cref="Foundation.NSMutableArray{TKey}"/> contains any elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns><see langword="true"/> if <paramref name="source"/> contains any elements; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static bool Any<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Any ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Determines whether any element of <see cref="Foundation.NSMutableArray{TKey}"/> satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns><see langword="true"/> if any element in <paramref name="source"/> passes the test in <paramref name="predicate"/>; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static bool Any<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Any ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Determines whether all elements of <see cref="Foundation.NSMutableArray{TKey}"/> satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns><see langword="true"/> if every element in <paramref name="source"/> passes the test in <paramref name="predicate"/>, or if the collection is empty; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static bool All<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.All ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the number of elements in <see cref="Foundation.NSMutableArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The number of elements in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static int Count<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Count ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the number of elements in <see cref="Foundation.NSMutableArray{TKey}"/> that satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static int Count<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Count ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns a <see cref="long"/> that represents the total number of elements in <see cref="Foundation.NSMutableArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The number of elements in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static long LongCount<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.LongCount ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns a <see cref="long"/> that represents the number of elements in <see cref="Foundation.NSMutableArray{TKey}"/> that satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static long LongCount<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.LongCount ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Filters elements of <see cref="Foundation.NSMutableArray{TKey}"/> based on a predicate.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Where ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Filters elements of <see cref="Foundation.NSMutableArray{TKey}"/> based on a predicate that incorporates each element's index.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element; the second parameter represents the zero-based index of the element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Where ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Projects each element of <see cref="Foundation.NSMutableArray{TKey}"/> into a new form.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TResult">The type of the value returned by <paramref name="selector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="selector">A transform function to apply to each element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableArray<TKey> source, Func<TKey, TResult> selector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (selector);
+			return Enumerable.Select ((IEnumerable<TKey>) source, selector);
+		}
+
+		/// <summary>Projects each element of <see cref="Foundation.NSMutableArray{TKey}"/> into a new form by incorporating each element's index.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TResult">The type of the value returned by <paramref name="selector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="selector">A transform function to apply to each element; the second parameter represents the zero-based index of the element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableArray<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (selector);
+			return Enumerable.Select ((IEnumerable<TKey>) source, selector);
+		}
+
+		/// <summary>Sorts the elements of <see cref="Foundation.NSMutableArray{TKey}"/> in ascending order according to a key.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TOrderKey">The type of the key returned by <paramref name="keySelector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="keySelector">A function to extract a key from an element.</param>
+		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted according to a key.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
+		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (keySelector);
+			return Enumerable.OrderBy ((IEnumerable<TKey>) source, keySelector);
+		}
+
+		/// <summary>Sorts the elements of <see cref="Foundation.NSMutableArray{TKey}"/> in descending order according to a key.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TOrderKey">The type of the key returned by <paramref name="keySelector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="keySelector">A function to extract a key from an element.</param>
+		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted in descending order according to a key.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
+		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (keySelector);
+			return Enumerable.OrderByDescending ((IEnumerable<TKey>) source, keySelector);
+		}
+
+		/// <summary>Bypasses a specified number of elements in <see cref="Foundation.NSMutableArray{TKey}"/> and returns the remaining elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="count">The number of elements to skip before returning the remaining elements.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements after the skipped ones.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSMutableArray<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Skip ((IEnumerable<TKey>) source, count);
+		}
+
+		/// <summary>Bypasses elements in <see cref="Foundation.NSMutableArray{TKey}"/> as long as a condition is true, then returns the remaining elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the elements starting at the first element that does not satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.SkipWhile ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns a specified number of contiguous elements from the start of <see cref="Foundation.NSMutableArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="count">The number of elements to return.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the specified number of elements from the start of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSMutableArray<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Take ((IEnumerable<TKey>) source, count);
+		}
+
+		/// <summary>Returns elements from <see cref="Foundation.NSMutableArray{TKey}"/> as long as a specified condition is true.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> as long as the condition is true.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.TakeWhile ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns distinct elements from <see cref="Foundation.NSMutableArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains distinct elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Distinct ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Inverts the order of the elements in <see cref="Foundation.NSMutableArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements correspond to those of <paramref name="source"/> in reverse order.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Reverse ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Concatenates <see cref="Foundation.NSMutableArray{TKey}"/> with another sequence.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="second">The sequence to concatenate to <paramref name="source"/>.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the concatenated elements of the two sequences.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="second"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSMutableArray<TKey> source, IEnumerable<TKey> second) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (second);
+			return Enumerable.Concat ((IEnumerable<TKey>) source, second);
+		}
+
+		/// <summary>Creates a <see cref="List{T}"/> from <see cref="Foundation.NSMutableArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>A <see cref="List{T}"/> that contains elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static List<TKey> ToList<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ToList ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Creates an array from <see cref="Foundation.NSMutableArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An array that contains elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey [] ToArray<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ToArray ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Applies an accumulator function over <see cref="Foundation.NSMutableArray{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="func">An accumulator function to be invoked on each element.</param>
+		/// <returns>The final accumulator value.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey Aggregate<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (func);
+			return Enumerable.Aggregate ((IEnumerable<TKey>) source, func);
+		}
+
+		/// <summary>Applies an accumulator function over <see cref="Foundation.NSMutableArray{TKey}"/> with a seed value.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TAccumulate">The type of the accumulator value.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="seed">The initial accumulator value.</param>
+		/// <param name="func">An accumulator function to be invoked on each element.</param>
+		/// <returns>The final accumulator value.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
+		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSMutableArray<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (func);
+			return Enumerable.Aggregate ((IEnumerable<TKey>) source, seed, func);
+		}
+
+		// NSOrderedSet<TKey>
+		/// <summary>Returns the first element of <see cref="Foundation.NSOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The first element in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey First<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.First ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the first element of <see cref="Foundation.NSOrderedSet{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey First<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.First ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the first element of <see cref="Foundation.NSOrderedSet{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The first element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the first element of <see cref="Foundation.NSOrderedSet{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The last element in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey Last<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Last ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSOrderedSet{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey Last<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Last ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSOrderedSet{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The last element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSOrderedSet{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The single element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty or contains more than one element.</exception>
+		public static TKey Single<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Single ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSOrderedSet{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element or more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey Single<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Single ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSOrderedSet{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The single element of <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> contains more than one element.</exception>
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSOrderedSet{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the element at a specified index in <see cref="Foundation.NSOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="index">The zero-based index of the element to retrieve.</param>
+		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="index"/> is less than 0 or greater than or equal to the number of elements in <paramref name="source"/>.</exception>
+		public static TKey ElementAt<TKey> (this Foundation.NSOrderedSet<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ElementAt ((IEnumerable<TKey>) source, index);
+		}
+
+		/// <summary>Returns the element at a specified index in <see cref="Foundation.NSOrderedSet{TKey}"/>, or <see langword="null"/> if the index is out of range.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="index">The zero-based index of the element to retrieve.</param>
+		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>, or <see langword="null"/> if the index is out of range.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ElementAtOrDefault ((IEnumerable<TKey>) source, index);
+		}
+
+		/// <summary>Determines whether <see cref="Foundation.NSOrderedSet{TKey}"/> contains any elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns><see langword="true"/> if <paramref name="source"/> contains any elements; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static bool Any<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Any ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Determines whether any element of <see cref="Foundation.NSOrderedSet{TKey}"/> satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns><see langword="true"/> if any element in <paramref name="source"/> passes the test in <paramref name="predicate"/>; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static bool Any<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Any ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Determines whether all elements of <see cref="Foundation.NSOrderedSet{TKey}"/> satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns><see langword="true"/> if every element in <paramref name="source"/> passes the test in <paramref name="predicate"/>, or if the collection is empty; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static bool All<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.All ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the number of elements in <see cref="Foundation.NSOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The number of elements in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static int Count<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Count ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the number of elements in <see cref="Foundation.NSOrderedSet{TKey}"/> that satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static int Count<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Count ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns a <see cref="long"/> that represents the total number of elements in <see cref="Foundation.NSOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The number of elements in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static long LongCount<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.LongCount ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns a <see cref="long"/> that represents the number of elements in <see cref="Foundation.NSOrderedSet{TKey}"/> that satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static long LongCount<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.LongCount ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Filters elements of <see cref="Foundation.NSOrderedSet{TKey}"/> based on a predicate.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Where ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Filters elements of <see cref="Foundation.NSOrderedSet{TKey}"/> based on a predicate that incorporates each element's index.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element; the second parameter represents the zero-based index of the element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Where ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Projects each element of <see cref="Foundation.NSOrderedSet{TKey}"/> into a new form.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TResult">The type of the value returned by <paramref name="selector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="selector">A transform function to apply to each element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, TResult> selector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (selector);
+			return Enumerable.Select ((IEnumerable<TKey>) source, selector);
+		}
+
+		/// <summary>Projects each element of <see cref="Foundation.NSOrderedSet{TKey}"/> into a new form by incorporating each element's index.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TResult">The type of the value returned by <paramref name="selector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="selector">A transform function to apply to each element; the second parameter represents the zero-based index of the element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (selector);
+			return Enumerable.Select ((IEnumerable<TKey>) source, selector);
+		}
+
+		/// <summary>Sorts the elements of <see cref="Foundation.NSOrderedSet{TKey}"/> in ascending order according to a key.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TOrderKey">The type of the key returned by <paramref name="keySelector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="keySelector">A function to extract a key from an element.</param>
+		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted according to a key.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
+		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (keySelector);
+			return Enumerable.OrderBy ((IEnumerable<TKey>) source, keySelector);
+		}
+
+		/// <summary>Sorts the elements of <see cref="Foundation.NSOrderedSet{TKey}"/> in descending order according to a key.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TOrderKey">The type of the key returned by <paramref name="keySelector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="keySelector">A function to extract a key from an element.</param>
+		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted in descending order according to a key.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
+		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (keySelector);
+			return Enumerable.OrderByDescending ((IEnumerable<TKey>) source, keySelector);
+		}
+
+		/// <summary>Bypasses a specified number of elements in <see cref="Foundation.NSOrderedSet{TKey}"/> and returns the remaining elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="count">The number of elements to skip before returning the remaining elements.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements after the skipped ones.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSOrderedSet<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Skip ((IEnumerable<TKey>) source, count);
+		}
+
+		/// <summary>Bypasses elements in <see cref="Foundation.NSOrderedSet{TKey}"/> as long as a condition is true, then returns the remaining elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the elements starting at the first element that does not satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.SkipWhile ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns a specified number of contiguous elements from the start of <see cref="Foundation.NSOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="count">The number of elements to return.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the specified number of elements from the start of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSOrderedSet<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Take ((IEnumerable<TKey>) source, count);
+		}
+
+		/// <summary>Returns elements from <see cref="Foundation.NSOrderedSet{TKey}"/> as long as a specified condition is true.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> as long as the condition is true.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.TakeWhile ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns distinct elements from <see cref="Foundation.NSOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains distinct elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Distinct ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Inverts the order of the elements in <see cref="Foundation.NSOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements correspond to those of <paramref name="source"/> in reverse order.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Reverse ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Concatenates <see cref="Foundation.NSOrderedSet{TKey}"/> with another sequence.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="second">The sequence to concatenate to <paramref name="source"/>.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the concatenated elements of the two sequences.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="second"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSOrderedSet<TKey> source, IEnumerable<TKey> second) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (second);
+			return Enumerable.Concat ((IEnumerable<TKey>) source, second);
+		}
+
+		/// <summary>Creates a <see cref="List{T}"/> from <see cref="Foundation.NSOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>A <see cref="List{T}"/> that contains elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static List<TKey> ToList<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ToList ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Creates an array from <see cref="Foundation.NSOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An array that contains elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey [] ToArray<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ToArray ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Applies an accumulator function over <see cref="Foundation.NSOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="func">An accumulator function to be invoked on each element.</param>
+		/// <returns>The final accumulator value.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey Aggregate<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (func);
+			return Enumerable.Aggregate ((IEnumerable<TKey>) source, func);
+		}
+
+		/// <summary>Applies an accumulator function over <see cref="Foundation.NSOrderedSet{TKey}"/> with a seed value.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TAccumulate">The type of the accumulator value.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="seed">The initial accumulator value.</param>
+		/// <param name="func">An accumulator function to be invoked on each element.</param>
+		/// <returns>The final accumulator value.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
+		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSOrderedSet<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (func);
+			return Enumerable.Aggregate ((IEnumerable<TKey>) source, seed, func);
+		}
+
+		// NSMutableOrderedSet<TKey>
+		/// <summary>Returns the first element of <see cref="Foundation.NSMutableOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The first element in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey First<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.First ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the first element of <see cref="Foundation.NSMutableOrderedSet{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey First<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.First ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the first element of <see cref="Foundation.NSMutableOrderedSet{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The first element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the first element of <see cref="Foundation.NSMutableOrderedSet{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSMutableOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The last element in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey Last<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Last ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSMutableOrderedSet{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey Last<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Last ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSMutableOrderedSet{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The last element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the last element of <see cref="Foundation.NSMutableOrderedSet{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSMutableOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The single element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty or contains more than one element.</exception>
+		public static TKey Single<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Single ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSMutableOrderedSet{TKey}"/> that satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when no element or more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey Single<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Single ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSMutableOrderedSet{TKey}"/>, or <see langword="null"/> if the collection is empty.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The single element of <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> contains more than one element.</exception>
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the only element of <see cref="Foundation.NSMutableOrderedSet{TKey}"/> that satisfies a condition, or <see langword="null"/> if no such element is found.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the element at a specified index in <see cref="Foundation.NSMutableOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="index">The zero-based index of the element to retrieve.</param>
+		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="index"/> is less than 0 or greater than or equal to the number of elements in <paramref name="source"/>.</exception>
+		public static TKey ElementAt<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ElementAt ((IEnumerable<TKey>) source, index);
+		}
+
+		/// <summary>Returns the element at a specified index in <see cref="Foundation.NSMutableOrderedSet{TKey}"/>, or <see langword="null"/> if the index is out of range.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="index">The zero-based index of the element to retrieve.</param>
+		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>, or <see langword="null"/> if the index is out of range.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ElementAtOrDefault ((IEnumerable<TKey>) source, index);
+		}
+
+		/// <summary>Determines whether <see cref="Foundation.NSMutableOrderedSet{TKey}"/> contains any elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns><see langword="true"/> if <paramref name="source"/> contains any elements; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static bool Any<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Any ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Determines whether any element of <see cref="Foundation.NSMutableOrderedSet{TKey}"/> satisfies a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns><see langword="true"/> if any element in <paramref name="source"/> passes the test in <paramref name="predicate"/>; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static bool Any<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Any ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Determines whether all elements of <see cref="Foundation.NSMutableOrderedSet{TKey}"/> satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns><see langword="true"/> if every element in <paramref name="source"/> passes the test in <paramref name="predicate"/>, or if the collection is empty; otherwise <see langword="false"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static bool All<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.All ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns the number of elements in <see cref="Foundation.NSMutableOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The number of elements in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static int Count<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Count ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns the number of elements in <see cref="Foundation.NSMutableOrderedSet{TKey}"/> that satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static int Count<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Count ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns a <see cref="long"/> that represents the total number of elements in <see cref="Foundation.NSMutableOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>The number of elements in <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static long LongCount<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.LongCount ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Returns a <see cref="long"/> that represents the number of elements in <see cref="Foundation.NSMutableOrderedSet{TKey}"/> that satisfy a condition.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static long LongCount<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.LongCount ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Filters elements of <see cref="Foundation.NSMutableOrderedSet{TKey}"/> based on a predicate.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Where ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Filters elements of <see cref="Foundation.NSMutableOrderedSet{TKey}"/> based on a predicate that incorporates each element's index.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element; the second parameter represents the zero-based index of the element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.Where ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Projects each element of <see cref="Foundation.NSMutableOrderedSet{TKey}"/> into a new form.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TResult">The type of the value returned by <paramref name="selector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="selector">A transform function to apply to each element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, TResult> selector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (selector);
+			return Enumerable.Select ((IEnumerable<TKey>) source, selector);
+		}
+
+		/// <summary>Projects each element of <see cref="Foundation.NSMutableOrderedSet{TKey}"/> into a new form by incorporating each element's index.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TResult">The type of the value returned by <paramref name="selector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="selector">A transform function to apply to each element; the second parameter represents the zero-based index of the element.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (selector);
+			return Enumerable.Select ((IEnumerable<TKey>) source, selector);
+		}
+
+		/// <summary>Sorts the elements of <see cref="Foundation.NSMutableOrderedSet{TKey}"/> in ascending order according to a key.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TOrderKey">The type of the key returned by <paramref name="keySelector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="keySelector">A function to extract a key from an element.</param>
+		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted according to a key.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
+		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (keySelector);
+			return Enumerable.OrderBy ((IEnumerable<TKey>) source, keySelector);
+		}
+
+		/// <summary>Sorts the elements of <see cref="Foundation.NSMutableOrderedSet{TKey}"/> in descending order according to a key.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TOrderKey">The type of the key returned by <paramref name="keySelector"/>.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="keySelector">A function to extract a key from an element.</param>
+		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted in descending order according to a key.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
+		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (keySelector);
+			return Enumerable.OrderByDescending ((IEnumerable<TKey>) source, keySelector);
+		}
+
+		/// <summary>Bypasses a specified number of elements in <see cref="Foundation.NSMutableOrderedSet{TKey}"/> and returns the remaining elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="count">The number of elements to skip before returning the remaining elements.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements after the skipped ones.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Skip ((IEnumerable<TKey>) source, count);
+		}
+
+		/// <summary>Bypasses elements in <see cref="Foundation.NSMutableOrderedSet{TKey}"/> as long as a condition is true, then returns the remaining elements.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the elements starting at the first element that does not satisfy the condition.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.SkipWhile ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns a specified number of contiguous elements from the start of <see cref="Foundation.NSMutableOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="count">The number of elements to return.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the specified number of elements from the start of <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Take ((IEnumerable<TKey>) source, count);
+		}
+
+		/// <summary>Returns elements from <see cref="Foundation.NSMutableOrderedSet{TKey}"/> as long as a specified condition is true.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="predicate">A function to test each element for a condition.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> as long as the condition is true.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (predicate);
+			return Enumerable.TakeWhile ((IEnumerable<TKey>) source, predicate);
+		}
+
+		/// <summary>Returns distinct elements from <see cref="Foundation.NSMutableOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains distinct elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Distinct ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Inverts the order of the elements in <see cref="Foundation.NSMutableOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> whose elements correspond to those of <paramref name="source"/> in reverse order.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.Reverse ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Concatenates <see cref="Foundation.NSMutableOrderedSet{TKey}"/> with another sequence.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="second">The sequence to concatenate to <paramref name="source"/>.</param>
+		/// <returns>An <see cref="IEnumerable{T}"/> that contains the concatenated elements of the two sequences.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="second"/> is <see langword="null"/>.</exception>
+		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, IEnumerable<TKey> second) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (second);
+			return Enumerable.Concat ((IEnumerable<TKey>) source, second);
+		}
+
+		/// <summary>Creates a <see cref="List{T}"/> from <see cref="Foundation.NSMutableOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>A <see cref="List{T}"/> that contains elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static List<TKey> ToList<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ToList ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Creates an array from <see cref="Foundation.NSMutableOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <returns>An array that contains elements from <paramref name="source"/>.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
+		public static TKey [] ToArray<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			return Enumerable.ToArray ((IEnumerable<TKey>) source);
+		}
+
+		/// <summary>Applies an accumulator function over <see cref="Foundation.NSMutableOrderedSet{TKey}"/>.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="func">An accumulator function to be invoked on each element.</param>
+		/// <returns>The final accumulator value.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
+		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
+		public static TKey Aggregate<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (func);
+			return Enumerable.Aggregate ((IEnumerable<TKey>) source, func);
+		}
+
+		/// <summary>Applies an accumulator function over <see cref="Foundation.NSMutableOrderedSet{TKey}"/> with a seed value.</summary>
+		/// <typeparam name="TKey">The element type of the collection.</typeparam>
+		/// <typeparam name="TAccumulate">The type of the accumulator value.</typeparam>
+		/// <param name="source">The source collection.</param>
+		/// <param name="seed">The initial accumulator value.</param>
+		/// <param name="func">An accumulator function to be invoked on each element.</param>
+		/// <returns>The final accumulator value.</returns>
+		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
+		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSMutableOrderedSet<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, Foundation.INativeObject
+		{
+			ArgumentNullException.ThrowIfNull (source);
+			ArgumentNullException.ThrowIfNull (func);
+			return Enumerable.Aggregate ((IEnumerable<TKey>) source, seed, func);
 		}
 	}
 }
diff --git a/tests/monotouch-test/Foundation/NSCollectionLinqTest.cs b/tests/monotouch-test/Foundation/NSCollectionLinqTest.cs
new file mode 100644
index 000000000000..23ae501d5075
--- /dev/null
+++ b/tests/monotouch-test/Foundation/NSCollectionLinqTest.cs
@@ -0,0 +1,1521 @@
+using System.Collections.Generic;
+using System.Linq;
+
+using Foundation;
+
+using NUnit.Framework;
+
+namespace MonoTouchFixtures.Foundation {
+
+[TestFixture]
+[Preserve (AllMembers = true)]
+public class NSCollectionLinqTest {
+
+// ----- helpers -----
+
+static NSString S (string s) => (NSString) s;
+
+static NSSet<NSString> MakeSet (params string [] items)
+{
+return new NSSet<NSString> (items.Select (S).ToArray ());
+}
+
+static NSMutableSet<NSString> MakeMutableSet (params string [] items)
+{
+return new NSMutableSet<NSString> (items.Select (S).ToArray ());
+}
+
+static NSArray<NSString> MakeArray (params string [] items)
+{
+return NSArray<NSString>.FromNSObjects (items.Select (S).ToArray ());
+}
+
+static NSMutableArray<NSString> MakeMutableArray (params string [] items)
+{
+var arr = new NSMutableArray<NSString> ();
+foreach (var s in items)
+arr.Add (S (s));
+return arr;
+}
+
+static NSOrderedSet<NSString> MakeOrderedSet (params string [] items)
+{
+return new NSOrderedSet<NSString> (items.Select (S).ToArray ());
+}
+
+static NSMutableOrderedSet<NSString> MakeMutableOrderedSet (params string [] items)
+{
+var set = new NSMutableOrderedSet<NSString> ();
+foreach (var s in items)
+set.Add (S (s));
+return set;
+}
+
+// ===== NSSet<T> =====
+
+[Test]
+public void NSSet_First ()
+{
+using var set = MakeSet ("a");
+var first = set.First ();
+Assert.That (first.ToString (), Is.EqualTo ("a"), "First");
+}
+
+[Test]
+public void NSSet_First_Predicate ()
+{
+using var set = MakeSet ("a", "b", "c");
+var found = set.First (s => s.ToString () == "b");
+Assert.That (found.ToString (), Is.EqualTo ("b"), "First predicate");
+}
+
+[Test]
+public void NSSet_First_Empty_Throws ()
+{
+using var set = MakeSet ();
+Assert.Throws<InvalidOperationException> (() => set.First ());
+}
+
+[Test]
+public void NSSet_FirstOrDefault_Empty ()
+{
+using var set = MakeSet ();
+Assert.That (set.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
+}
+
+[Test]
+public void NSSet_FirstOrDefault ()
+{
+using var set = MakeSet ("x");
+Assert.That (set.FirstOrDefault (), Is.Not.Null, "FirstOrDefault");
+}
+
+[Test]
+public void NSSet_FirstOrDefault_Predicate_NoMatch ()
+{
+using var set = MakeSet ("a", "b");
+Assert.That (set.FirstOrDefault (s => s.ToString () == "z"), Is.Null, "no match");
+}
+
+[Test]
+public void NSSet_Last ()
+{
+using var set = MakeSet ("a");
+var last = set.Last ();
+Assert.That (last.ToString (), Is.EqualTo ("a"), "Last");
+}
+
+[Test]
+public void NSSet_Last_Predicate ()
+{
+using var set = MakeSet ("a", "b", "c");
+var found = set.Last (s => s.ToString () != "c");
+Assert.That (found, Is.Not.Null, "Last predicate not null");
+}
+
+[Test]
+public void NSSet_Last_Empty_Throws ()
+{
+using var set = MakeSet ();
+Assert.Throws<InvalidOperationException> (() => set.Last ());
+}
+
+[Test]
+public void NSSet_LastOrDefault_Empty ()
+{
+using var set = MakeSet ();
+Assert.That (set.LastOrDefault (), Is.Null, "LastOrDefault empty");
+}
+
+[Test]
+public void NSSet_LastOrDefault_Predicate_NoMatch ()
+{
+using var set = MakeSet ("a");
+Assert.That (set.LastOrDefault (s => s.ToString () == "z"), Is.Null, "LastOrDefault no match");
+}
+
+[Test]
+public void NSSet_Single ()
+{
+using var set = MakeSet ("only");
+Assert.That (set.Single ().ToString (), Is.EqualTo ("only"), "Single");
+}
+
+[Test]
+public void NSSet_Single_Throws_OnMultiple ()
+{
+using var set = MakeSet ("a", "b");
+Assert.Throws<InvalidOperationException> (() => set.Single ());
+}
+
+[Test]
+public void NSSet_SingleOrDefault_Empty ()
+{
+using var set = MakeSet ();
+Assert.That (set.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
+}
+
+[Test]
+public void NSSet_SingleOrDefault_Predicate ()
+{
+using var set = MakeSet ("a", "b");
+Assert.That (set.SingleOrDefault (s => s.ToString () == "a")?.ToString (), Is.EqualTo ("a"), "SingleOrDefault predicate");
+}
+
+[Test]
+public void NSSet_Any_Empty ()
+{
+using var set = MakeSet ();
+Assert.That (set.Any (), Is.False, "Any empty");
+}
+
+[Test]
+public void NSSet_Any_NonEmpty ()
+{
+using var set = MakeSet ("a");
+Assert.That (set.Any (), Is.True, "Any non-empty");
+}
+
+[Test]
+public void NSSet_Any_Predicate ()
+{
+using var set = MakeSet ("a", "b");
+Assert.That (set.Any (s => s.ToString () == "b"), Is.True, "Any predicate true");
+Assert.That (set.Any (s => s.ToString () == "z"), Is.False, "Any predicate false");
+}
+
+[Test]
+public void NSSet_All ()
+{
+using var set = MakeSet ("ab", "abc");
+Assert.That (set.All (s => s.Length > 1), Is.True, "All true");
+Assert.That (set.All (s => s.Length > 2), Is.False, "All false");
+}
+
+[Test]
+public void NSSet_Count ()
+{
+using var set = MakeSet ("a", "b", "c");
+Assert.That (set.Count (), Is.EqualTo (3), "Count");
+Assert.That (set.Count (s => s.ToString () == "a"), Is.EqualTo (1), "Count predicate");
+}
+
+[Test]
+public void NSSet_LongCount ()
+{
+using var set = MakeSet ("a", "b");
+Assert.That (set.LongCount (), Is.EqualTo (2L), "LongCount");
+Assert.That (set.LongCount (s => s.ToString () == "a"), Is.EqualTo (1L), "LongCount predicate");
+}
+
+[Test]
+public void NSSet_Where ()
+{
+using var set = MakeSet ("a", "bb", "ccc");
+var result = set.Where (s => s.Length > 1).ToList ();
+Assert.That (result.Count, Is.EqualTo (2), "Where count");
+}
+
+[Test]
+public void NSSet_Where_Index ()
+{
+using var arr = MakeOrderedSet ("a", "b", "c");
+var result = arr.Where ((s, i) => i % 2 == 0).ToList ();
+Assert.That (result.Count, Is.EqualTo (2), "Where index count");
+}
+
+[Test]
+public void NSSet_Select ()
+{
+using var set = MakeSet ("hello");
+var lengths = set.Select (s => s.Length).ToList ();
+Assert.That (lengths, Contains.Item (5), "Select length");
+}
+
+[Test]
+public void NSSet_Select_Index ()
+{
+using var arr = MakeOrderedSet ("a", "b", "c");
+var indexed = arr.Select ((s, i) => $"{i}:{s}").ToList ();
+Assert.That (indexed [0], Is.EqualTo ("0:a"), "Select index 0");
+Assert.That (indexed [1], Is.EqualTo ("1:b"), "Select index 1");
+}
+
+[Test]
+public void NSSet_OrderBy ()
+{
+using var set = MakeSet ("banana", "apple", "cherry");
+var sorted = set.OrderBy (s => s.ToString ()).ToList ();
+Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
+Assert.That (sorted [2].ToString (), Is.EqualTo ("cherry"), "OrderBy last");
+}
+
+[Test]
+public void NSSet_OrderByDescending ()
+{
+using var set = MakeSet ("banana", "apple", "cherry");
+var sorted = set.OrderByDescending (s => s.ToString ()).ToList ();
+Assert.That (sorted [0].ToString (), Is.EqualTo ("cherry"), "OrderByDesc first");
+}
+
+[Test]
+public void NSSet_Distinct ()
+{
+using var set = MakeSet ("a", "b", "b");
+// NSSet already ensures uniqueness, but verify Distinct works
+var distinct = set.Distinct ().ToList ();
+Assert.That (distinct.Count, Is.EqualTo (2), "Distinct count");
+}
+
+[Test]
+public void NSSet_Reverse ()
+{
+using var arr = MakeOrderedSet ("a", "b", "c");
+var reversed = arr.Reverse ().ToList ();
+Assert.That (reversed [0].ToString (), Is.EqualTo ("c"), "Reverse first");
+Assert.That (reversed [2].ToString (), Is.EqualTo ("a"), "Reverse last");
+}
+
+[Test]
+public void NSSet_Concat ()
+{
+using var set = MakeSet ("a", "b");
+var extra = new [] { S ("c"), S ("d") };
+var all = set.Concat (extra).ToList ();
+Assert.That (all.Count, Is.EqualTo (4), "Concat count");
+}
+
+[Test]
+public void NSSet_Skip_Take ()
+{
+using var arr = MakeOrderedSet ("a", "b", "c", "d");
+var sliced = arr.Skip (1).Take (2).ToList ();
+Assert.That (sliced.Count, Is.EqualTo (2), "Skip/Take count");
+Assert.That (sliced [0].ToString (), Is.EqualTo ("b"), "Skip/Take first");
+}
+
+[Test]
+public void NSSet_SkipWhile_TakeWhile ()
+{
+using var arr = MakeOrderedSet ("a", "b", "c");
+var skipped = arr.SkipWhile (s => s.ToString () == "a").ToList ();
+Assert.That (skipped.Count, Is.EqualTo (2), "SkipWhile count");
+
+var taken = arr.TakeWhile (s => s.ToString () != "c").ToList ();
+Assert.That (taken.Count, Is.EqualTo (2), "TakeWhile count");
+}
+
+[Test]
+public void NSSet_ElementAt ()
+{
+using var arr = MakeOrderedSet ("a", "b", "c");
+Assert.That (arr.ElementAt (1).ToString (), Is.EqualTo ("b"), "ElementAt");
+}
+
+[Test]
+public void NSSet_ElementAtOrDefault ()
+{
+using var arr = MakeOrderedSet ("a", "b");
+Assert.That (arr.ElementAtOrDefault (0), Is.Not.Null, "ElementAtOrDefault in range");
+Assert.That (arr.ElementAtOrDefault (99), Is.Null, "ElementAtOrDefault out of range");
+}
+
+[Test]
+public void NSSet_ToList ()
+{
+using var set = MakeSet ("a", "b");
+var list = set.ToList ();
+Assert.That (list, Is.TypeOf<List<NSString>> (), "ToList type");
+Assert.That (list.Count, Is.EqualTo (2), "ToList count");
+}
+
+[Test]
+public void NSSet_ToArray ()
+{
+using var set = MakeSet ("a", "b");
+var arr = set.ToArray ();
+Assert.That (arr, Is.TypeOf<NSString []> (), "ToArray type");
+Assert.That (arr.Length, Is.EqualTo (2), "ToArray length");
+}
+
+[Test]
+public void NSSet_Aggregate ()
+{
+using var arr = MakeOrderedSet ("a", "b", "c");
+var result = arr.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
+Assert.That (result.ToString (), Is.EqualTo ("abc"), "Aggregate");
+}
+
+[Test]
+public void NSSet_Aggregate_Seed ()
+{
+using var arr = MakeOrderedSet ("a", "b", "c");
+var result = arr.Aggregate ("", (acc, s) => acc + s.ToString ());
+Assert.That (result, Is.EqualTo ("abc"), "Aggregate seed");
+}
+
+// ===== NSMutableSet<T> =====
+
+[Test]
+public void NSMutableSet_First ()
+{
+using var set = MakeMutableSet ("a");
+Assert.That (set.First ().ToString (), Is.EqualTo ("a"), "First");
+}
+
+[Test]
+public void NSMutableSet_FirstOrDefault_Empty ()
+{
+using var set = MakeMutableSet ();
+Assert.That (set.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
+}
+
+[Test]
+public void NSMutableSet_Last ()
+{
+using var set = MakeMutableSet ("a");
+Assert.That (set.Last ().ToString (), Is.EqualTo ("a"), "Last");
+}
+
+[Test]
+public void NSMutableSet_LastOrDefault_Empty ()
+{
+using var set = MakeMutableSet ();
+Assert.That (set.LastOrDefault (), Is.Null, "LastOrDefault empty");
+}
+
+[Test]
+public void NSMutableSet_Single ()
+{
+using var set = MakeMutableSet ("only");
+Assert.That (set.Single ().ToString (), Is.EqualTo ("only"), "Single");
+}
+
+[Test]
+public void NSMutableSet_SingleOrDefault_Empty ()
+{
+using var set = MakeMutableSet ();
+Assert.That (set.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
+}
+
+[Test]
+public void NSMutableSet_Any ()
+{
+using var set = MakeMutableSet ();
+Assert.That (set.Any (), Is.False, "Any empty");
+using var set2 = MakeMutableSet ("a");
+Assert.That (set2.Any (), Is.True, "Any non-empty");
+}
+
+[Test]
+public void NSMutableSet_All ()
+{
+using var set = MakeMutableSet ("ab", "abc");
+Assert.That (set.All (s => s.Length > 1), Is.True, "All true");
+}
+
+[Test]
+public void NSMutableSet_Count ()
+{
+using var set = MakeMutableSet ("a", "b", "c");
+Assert.That (set.Count (), Is.EqualTo (3), "Count");
+}
+
+[Test]
+public void NSMutableSet_LongCount ()
+{
+using var set = MakeMutableSet ("a", "b");
+Assert.That (set.LongCount (), Is.EqualTo (2L), "LongCount");
+}
+
+[Test]
+public void NSMutableSet_Where ()
+{
+using var set = MakeMutableSet ("a", "bb", "ccc");
+var result = set.Where (s => s.Length > 1).ToList ();
+Assert.That (result.Count, Is.EqualTo (2), "Where count");
+}
+
+[Test]
+public void NSMutableSet_Select ()
+{
+using var set = MakeMutableSet ("hello");
+var lengths = set.Select (s => s.Length).ToList ();
+Assert.That (lengths, Contains.Item (5), "Select length");
+}
+
+[Test]
+public void NSMutableSet_OrderBy ()
+{
+using var set = MakeMutableSet ("banana", "apple", "cherry");
+var sorted = set.OrderBy (s => s.ToString ()).ToList ();
+Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
+}
+
+[Test]
+public void NSMutableSet_Skip_Take ()
+{
+using var arr = MakeOrderedSet ("a", "b", "c", "d");
+var sliced = arr.Skip (1).Take (2).ToList ();
+Assert.That (sliced.Count, Is.EqualTo (2), "Skip/Take count");
+}
+
+[Test]
+public void NSMutableSet_ToList ()
+{
+using var set = MakeMutableSet ("a", "b");
+var list = set.ToList ();
+Assert.That (list.Count, Is.EqualTo (2), "ToList count");
+}
+
+[Test]
+public void NSMutableSet_ToArray ()
+{
+using var set = MakeMutableSet ("a", "b");
+var arr = set.ToArray ();
+Assert.That (arr.Length, Is.EqualTo (2), "ToArray length");
+}
+
+[Test]
+public void NSMutableSet_Aggregate ()
+{
+using var set = MakeMutableSet ("a");
+var result = set.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
+Assert.That (result.ToString (), Is.EqualTo ("a"), "Aggregate");
+}
+
+// ===== NSArray<T> =====
+
+[Test]
+public void NSArray_First ()
+{
+using var arr = MakeArray ("a", "b", "c");
+Assert.That (arr.First ().ToString (), Is.EqualTo ("a"), "First");
+}
+
+[Test]
+public void NSArray_First_Predicate ()
+{
+using var arr = MakeArray ("a", "b", "c");
+Assert.That (arr.First (s => s.ToString () == "b").ToString (), Is.EqualTo ("b"), "First predicate");
+}
+
+[Test]
+public void NSArray_First_Empty_Throws ()
+{
+using var arr = MakeArray ();
+Assert.Throws<InvalidOperationException> (() => arr.First ());
+}
+
+[Test]
+public void NSArray_FirstOrDefault_Empty ()
+{
+using var arr = MakeArray ();
+Assert.That (arr.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
+}
+
+[Test]
+public void NSArray_FirstOrDefault ()
+{
+using var arr = MakeArray ("x", "y");
+Assert.That (arr.FirstOrDefault ()?.ToString (), Is.EqualTo ("x"), "FirstOrDefault");
+}
+
+[Test]
+public void NSArray_FirstOrDefault_Predicate ()
+{
+using var arr = MakeArray ("a", "b", "c");
+Assert.That (arr.FirstOrDefault (s => s.ToString () == "b")?.ToString (), Is.EqualTo ("b"), "FirstOrDefault predicate match");
+Assert.That (arr.FirstOrDefault (s => s.ToString () == "z"), Is.Null, "FirstOrDefault predicate no match");
+}
+
+[Test]
+public void NSArray_Last ()
+{
+using var arr = MakeArray ("a", "b", "c");
+Assert.That (arr.Last ().ToString (), Is.EqualTo ("c"), "Last");
+}
+
+[Test]
+public void NSArray_Last_Predicate ()
+{
+using var arr = MakeArray ("a", "b", "c");
+Assert.That (arr.Last (s => s.ToString () != "c").ToString (), Is.EqualTo ("b"), "Last predicate");
+}
+
+[Test]
+public void NSArray_Last_Empty_Throws ()
+{
+using var arr = MakeArray ();
+Assert.Throws<InvalidOperationException> (() => arr.Last ());
+}
+
+[Test]
+public void NSArray_LastOrDefault_Empty ()
+{
+using var arr = MakeArray ();
+Assert.That (arr.LastOrDefault (), Is.Null, "LastOrDefault empty");
+}
+
+[Test]
+public void NSArray_LastOrDefault_Predicate_NoMatch ()
+{
+using var arr = MakeArray ("a", "b");
+Assert.That (arr.LastOrDefault (s => s.ToString () == "z"), Is.Null, "LastOrDefault no match");
+}
+
+[Test]
+public void NSArray_Single ()
+{
+using var arr = MakeArray ("only");
+Assert.That (arr.Single ().ToString (), Is.EqualTo ("only"), "Single");
+}
+
+[Test]
+public void NSArray_Single_Throws_OnEmpty ()
+{
+using var arr = MakeArray ();
+Assert.Throws<InvalidOperationException> (() => arr.Single ());
+}
+
+[Test]
+public void NSArray_Single_Throws_OnMultiple ()
+{
+using var arr = MakeArray ("a", "b");
+Assert.Throws<InvalidOperationException> (() => arr.Single ());
+}
+
+[Test]
+public void NSArray_SingleOrDefault_Empty ()
+{
+using var arr = MakeArray ();
+Assert.That (arr.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
+}
+
+[Test]
+public void NSArray_SingleOrDefault_Predicate ()
+{
+using var arr = MakeArray ("a", "b");
+Assert.That (arr.SingleOrDefault (s => s.ToString () == "a")?.ToString (), Is.EqualTo ("a"), "SingleOrDefault predicate match");
+Assert.That (arr.SingleOrDefault (s => s.ToString () == "z"), Is.Null, "SingleOrDefault predicate no match");
+}
+
+[Test]
+public void NSArray_ElementAt ()
+{
+using var arr = MakeArray ("a", "b", "c");
+Assert.That (arr.ElementAt (0).ToString (), Is.EqualTo ("a"), "ElementAt 0");
+Assert.That (arr.ElementAt (2).ToString (), Is.EqualTo ("c"), "ElementAt 2");
+}
+
+[Test]
+public void NSArray_ElementAt_OutOfRange_Throws ()
+{
+using var arr = MakeArray ("a");
+Assert.Throws<ArgumentOutOfRangeException> (() => arr.ElementAt (5));
+}
+
+[Test]
+public void NSArray_ElementAtOrDefault ()
+{
+using var arr = MakeArray ("a", "b");
+Assert.That (arr.ElementAtOrDefault (1)?.ToString (), Is.EqualTo ("b"), "ElementAtOrDefault in range");
+Assert.That (arr.ElementAtOrDefault (99), Is.Null, "ElementAtOrDefault out of range");
+}
+
+[Test]
+public void NSArray_Any ()
+{
+using var empty = MakeArray ();
+Assert.That (empty.Any (), Is.False, "Any empty");
+using var arr = MakeArray ("a");
+Assert.That (arr.Any (), Is.True, "Any non-empty");
+Assert.That (arr.Any (s => s.ToString () == "a"), Is.True, "Any predicate true");
+Assert.That (arr.Any (s => s.ToString () == "z"), Is.False, "Any predicate false");
+}
+
+[Test]
+public void NSArray_All ()
+{
+using var arr = MakeArray ("ab", "abc");
+Assert.That (arr.All (s => s.Length > 1), Is.True, "All true");
+Assert.That (arr.All (s => s.Length > 2), Is.False, "All false");
+}
+
+[Test]
+public void NSArray_Count ()
+{
+using var arr = MakeArray ("a", "b", "c");
+Assert.That (arr.Count (), Is.EqualTo (3), "Count");
+Assert.That (arr.Count (s => s.ToString () == "a"), Is.EqualTo (1), "Count predicate");
+}
+
+[Test]
+public void NSArray_LongCount ()
+{
+using var arr = MakeArray ("a", "b");
+Assert.That (arr.LongCount (), Is.EqualTo (2L), "LongCount");
+Assert.That (arr.LongCount (s => s.ToString () == "a"), Is.EqualTo (1L), "LongCount predicate");
+}
+
+[Test]
+public void NSArray_Where ()
+{
+using var arr = MakeArray ("a", "bb", "ccc");
+var result = arr.Where (s => s.Length > 1).ToList ();
+Assert.That (result.Count, Is.EqualTo (2), "Where count");
+}
+
+[Test]
+public void NSArray_Where_Index ()
+{
+using var arr = MakeArray ("a", "b", "c");
+var result = arr.Where ((s, i) => i % 2 == 0).ToList ();
+Assert.That (result.Count, Is.EqualTo (2), "Where index count");
+Assert.That (result [0].ToString (), Is.EqualTo ("a"), "Where index [0]");
+Assert.That (result [1].ToString (), Is.EqualTo ("c"), "Where index [1]");
+}
+
+[Test]
+public void NSArray_Select ()
+{
+using var arr = MakeArray ("hello", "world");
+var lengths = arr.Select (s => s.Length).ToList ();
+Assert.That (lengths [0], Is.EqualTo (5), "Select length [0]");
+Assert.That (lengths [1], Is.EqualTo (5), "Select length [1]");
+}
+
+[Test]
+public void NSArray_Select_Index ()
+{
+using var arr = MakeArray ("a", "b", "c");
+var indexed = arr.Select ((s, i) => $"{i}:{s}").ToList ();
+Assert.That (indexed [0], Is.EqualTo ("0:a"), "Select index 0");
+Assert.That (indexed [2], Is.EqualTo ("2:c"), "Select index 2");
+}
+
+[Test]
+public void NSArray_OrderBy ()
+{
+using var arr = MakeArray ("banana", "apple", "cherry");
+var sorted = arr.OrderBy (s => s.ToString ()).ToList ();
+Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
+Assert.That (sorted [1].ToString (), Is.EqualTo ("banana"), "OrderBy second");
+Assert.That (sorted [2].ToString (), Is.EqualTo ("cherry"), "OrderBy third");
+}
+
+[Test]
+public void NSArray_OrderByDescending ()
+{
+using var arr = MakeArray ("banana", "apple", "cherry");
+var sorted = arr.OrderByDescending (s => s.ToString ()).ToList ();
+Assert.That (sorted [0].ToString (), Is.EqualTo ("cherry"), "OrderByDesc first");
+Assert.That (sorted [2].ToString (), Is.EqualTo ("apple"), "OrderByDesc last");
+}
+
+[Test]
+public void NSArray_Skip ()
+{
+using var arr = MakeArray ("a", "b", "c", "d");
+var skipped = arr.Skip (2).ToList ();
+Assert.That (skipped.Count, Is.EqualTo (2), "Skip count");
+Assert.That (skipped [0].ToString (), Is.EqualTo ("c"), "Skip [0]");
+}
+
+[Test]
+public void NSArray_SkipWhile ()
+{
+using var arr = MakeArray ("a", "b", "c");
+var result = arr.SkipWhile (s => s.ToString () != "b").ToList ();
+Assert.That (result.Count, Is.EqualTo (2), "SkipWhile count");
+Assert.That (result [0].ToString (), Is.EqualTo ("b"), "SkipWhile first");
+}
+
+[Test]
+public void NSArray_Take ()
+{
+using var arr = MakeArray ("a", "b", "c");
+var taken = arr.Take (2).ToList ();
+Assert.That (taken.Count, Is.EqualTo (2), "Take count");
+Assert.That (taken [1].ToString (), Is.EqualTo ("b"), "Take [1]");
+}
+
+[Test]
+public void NSArray_TakeWhile ()
+{
+using var arr = MakeArray ("a", "b", "c");
+var taken = arr.TakeWhile (s => s.ToString () != "c").ToList ();
+Assert.That (taken.Count, Is.EqualTo (2), "TakeWhile count");
+}
+
+[Test]
+public void NSArray_Distinct ()
+{
+using var arr = MakeArray ("a", "a", "b");
+var distinct = arr.Distinct ().ToList ();
+Assert.That (distinct.Count, Is.EqualTo (2), "Distinct count");
+}
+
+[Test]
+public void NSArray_Reverse ()
+{
+using var arr = MakeArray ("a", "b", "c");
+var reversed = arr.Reverse ().ToList ();
+Assert.That (reversed [0].ToString (), Is.EqualTo ("c"), "Reverse [0]");
+Assert.That (reversed [2].ToString (), Is.EqualTo ("a"), "Reverse [2]");
+}
+
+[Test]
+public void NSArray_Concat ()
+{
+using var arr = MakeArray ("a", "b");
+var extra = new [] { S ("c") };
+var all = arr.Concat (extra).ToList ();
+Assert.That (all.Count, Is.EqualTo (3), "Concat count");
+Assert.That (all [2].ToString (), Is.EqualTo ("c"), "Concat last");
+}
+
+[Test]
+public void NSArray_ToList ()
+{
+using var arr = MakeArray ("a", "b", "c");
+var list = arr.ToList ();
+Assert.That (list, Is.TypeOf<List<NSString>> (), "ToList type");
+Assert.That (list.Count, Is.EqualTo (3), "ToList count");
+}
+
+[Test]
+public void NSArray_ToArray ()
+{
+using var arr = MakeArray ("a", "b");
+var result = arr.ToArray ();
+Assert.That (result, Is.TypeOf<NSString []> (), "ToArray type");
+Assert.That (result.Length, Is.EqualTo (2), "ToArray length");
+}
+
+[Test]
+public void NSArray_Aggregate ()
+{
+using var arr = MakeArray ("a", "b", "c");
+var result = arr.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
+Assert.That (result.ToString (), Is.EqualTo ("abc"), "Aggregate");
+}
+
+[Test]
+public void NSArray_Aggregate_Seed ()
+{
+using var arr = MakeArray ("a", "b", "c");
+var result = arr.Aggregate ("", (acc, s) => acc + s.ToString ());
+Assert.That (result, Is.EqualTo ("abc"), "Aggregate seed");
+}
+
+// ===== NSMutableArray<T> =====
+
+[Test]
+public void NSMutableArray_First ()
+{
+using var arr = MakeMutableArray ("a", "b");
+Assert.That (arr.First ().ToString (), Is.EqualTo ("a"), "First");
+}
+
+[Test]
+public void NSMutableArray_First_Empty_Throws ()
+{
+using var arr = MakeMutableArray ();
+Assert.Throws<InvalidOperationException> (() => arr.First ());
+}
+
+[Test]
+public void NSMutableArray_FirstOrDefault_Empty ()
+{
+using var arr = MakeMutableArray ();
+Assert.That (arr.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
+}
+
+[Test]
+public void NSMutableArray_FirstOrDefault ()
+{
+using var arr = MakeMutableArray ("x", "y");
+Assert.That (arr.FirstOrDefault ()?.ToString (), Is.EqualTo ("x"), "FirstOrDefault");
+}
+
+[Test]
+public void NSMutableArray_Last ()
+{
+using var arr = MakeMutableArray ("a", "b", "c");
+Assert.That (arr.Last ().ToString (), Is.EqualTo ("c"), "Last");
+}
+
+[Test]
+public void NSMutableArray_LastOrDefault_Empty ()
+{
+using var arr = MakeMutableArray ();
+Assert.That (arr.LastOrDefault (), Is.Null, "LastOrDefault empty");
+}
+
+[Test]
+public void NSMutableArray_Single ()
+{
+using var arr = MakeMutableArray ("only");
+Assert.That (arr.Single ().ToString (), Is.EqualTo ("only"), "Single");
+}
+
+[Test]
+public void NSMutableArray_Single_Throws_OnMultiple ()
+{
+using var arr = MakeMutableArray ("a", "b");
+Assert.Throws<InvalidOperationException> (() => arr.Single ());
+}
+
+[Test]
+public void NSMutableArray_SingleOrDefault_Empty ()
+{
+using var arr = MakeMutableArray ();
+Assert.That (arr.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
+}
+
+[Test]
+public void NSMutableArray_ElementAt ()
+{
+using var arr = MakeMutableArray ("a", "b", "c");
+Assert.That (arr.ElementAt (1).ToString (), Is.EqualTo ("b"), "ElementAt 1");
+}
+
+[Test]
+public void NSMutableArray_ElementAtOrDefault ()
+{
+using var arr = MakeMutableArray ("a");
+Assert.That (arr.ElementAtOrDefault (0)?.ToString (), Is.EqualTo ("a"), "ElementAtOrDefault in range");
+Assert.That (arr.ElementAtOrDefault (10), Is.Null, "ElementAtOrDefault out of range");
+}
+
+[Test]
+public void NSMutableArray_Any ()
+{
+using var empty = MakeMutableArray ();
+Assert.That (empty.Any (), Is.False, "Any empty");
+using var arr = MakeMutableArray ("a");
+Assert.That (arr.Any (), Is.True, "Any non-empty");
+}
+
+[Test]
+public void NSMutableArray_All ()
+{
+using var arr = MakeMutableArray ("ab", "abc");
+Assert.That (arr.All (s => s.Length > 1), Is.True, "All true");
+}
+
+[Test]
+public void NSMutableArray_Count ()
+{
+using var arr = MakeMutableArray ("a", "b", "c");
+Assert.That (arr.Count (), Is.EqualTo (3), "Count");
+}
+
+[Test]
+public void NSMutableArray_LongCount ()
+{
+using var arr = MakeMutableArray ("a", "b");
+Assert.That (arr.LongCount (), Is.EqualTo (2L), "LongCount");
+}
+
+[Test]
+public void NSMutableArray_Where ()
+{
+using var arr = MakeMutableArray ("a", "bb", "ccc");
+var result = arr.Where (s => s.Length > 1).ToList ();
+Assert.That (result.Count, Is.EqualTo (2), "Where count");
+}
+
+[Test]
+public void NSMutableArray_Select ()
+{
+using var arr = MakeMutableArray ("hello", "world");
+var lengths = arr.Select (s => s.Length).ToList ();
+Assert.That (lengths [0], Is.EqualTo (5), "Select [0]");
+}
+
+[Test]
+public void NSMutableArray_OrderBy ()
+{
+using var arr = MakeMutableArray ("banana", "apple", "cherry");
+var sorted = arr.OrderBy (s => s.ToString ()).ToList ();
+Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
+}
+
+[Test]
+public void NSMutableArray_OrderByDescending ()
+{
+using var arr = MakeMutableArray ("banana", "apple", "cherry");
+var sorted = arr.OrderByDescending (s => s.ToString ()).ToList ();
+Assert.That (sorted [0].ToString (), Is.EqualTo ("cherry"), "OrderByDesc first");
+}
+
+[Test]
+public void NSMutableArray_Skip_Take ()
+{
+using var arr = MakeMutableArray ("a", "b", "c", "d");
+var sliced = arr.Skip (1).Take (2).ToList ();
+Assert.That (sliced.Count, Is.EqualTo (2), "Skip/Take count");
+}
+
+[Test]
+public void NSMutableArray_SkipWhile_TakeWhile ()
+{
+using var arr = MakeMutableArray ("a", "b", "c");
+var skipped = arr.SkipWhile (s => s.ToString () == "a").ToList ();
+Assert.That (skipped.Count, Is.EqualTo (2), "SkipWhile count");
+var taken = arr.TakeWhile (s => s.ToString () != "c").ToList ();
+Assert.That (taken.Count, Is.EqualTo (2), "TakeWhile count");
+}
+
+[Test]
+public void NSMutableArray_Distinct ()
+{
+using var arr = MakeMutableArray ("a", "a", "b");
+var distinct = arr.Distinct ().ToList ();
+Assert.That (distinct.Count, Is.EqualTo (2), "Distinct count");
+}
+
+[Test]
+public void NSMutableArray_Reverse ()
+{
+using var arr = MakeMutableArray ("a", "b", "c");
+var reversed = arr.Reverse ().ToList ();
+Assert.That (reversed [0].ToString (), Is.EqualTo ("c"), "Reverse [0]");
+}
+
+[Test]
+public void NSMutableArray_Concat ()
+{
+using var arr = MakeMutableArray ("a");
+var all = arr.Concat (new [] { S ("b") }).ToList ();
+Assert.That (all.Count, Is.EqualTo (2), "Concat count");
+}
+
+[Test]
+public void NSMutableArray_ToList ()
+{
+using var arr = MakeMutableArray ("a", "b");
+var list = arr.ToList ();
+Assert.That (list.Count, Is.EqualTo (2), "ToList count");
+}
+
+[Test]
+public void NSMutableArray_ToArray ()
+{
+using var arr = MakeMutableArray ("a", "b");
+var result = arr.ToArray ();
+Assert.That (result.Length, Is.EqualTo (2), "ToArray length");
+}
+
+[Test]
+public void NSMutableArray_Aggregate ()
+{
+using var arr = MakeMutableArray ("a", "b", "c");
+var result = arr.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
+Assert.That (result.ToString (), Is.EqualTo ("abc"), "Aggregate");
+}
+
+[Test]
+public void NSMutableArray_Aggregate_Seed ()
+{
+using var arr = MakeMutableArray ("a", "b", "c");
+var result = arr.Aggregate (0, (acc, s) => acc + s.Length);
+Assert.That (result, Is.EqualTo (3), "Aggregate seed");
+}
+
+// ===== NSOrderedSet<T> =====
+
+[Test]
+public void NSOrderedSet_First ()
+{
+using var set = MakeOrderedSet ("a", "b", "c");
+Assert.That (set.First ().ToString (), Is.EqualTo ("a"), "First");
+}
+
+[Test]
+public void NSOrderedSet_First_Predicate ()
+{
+using var set = MakeOrderedSet ("a", "b", "c");
+Assert.That (set.First (s => s.ToString () == "c").ToString (), Is.EqualTo ("c"), "First predicate");
+}
+
+[Test]
+public void NSOrderedSet_First_Empty_Throws ()
+{
+using var set = MakeOrderedSet ();
+Assert.Throws<InvalidOperationException> (() => set.First ());
+}
+
+[Test]
+public void NSOrderedSet_FirstOrDefault_Empty ()
+{
+using var set = MakeOrderedSet ();
+Assert.That (set.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
+}
+
+[Test]
+public void NSOrderedSet_FirstOrDefault ()
+{
+using var set = MakeOrderedSet ("x", "y");
+Assert.That (set.FirstOrDefault ()?.ToString (), Is.EqualTo ("x"), "FirstOrDefault");
+}
+
+[Test]
+public void NSOrderedSet_Last ()
+{
+using var set = MakeOrderedSet ("a", "b", "c");
+Assert.That (set.Last ().ToString (), Is.EqualTo ("c"), "Last");
+}
+
+[Test]
+public void NSOrderedSet_Last_Predicate ()
+{
+using var set = MakeOrderedSet ("a", "b", "c");
+Assert.That (set.Last (s => s.ToString () != "c").ToString (), Is.EqualTo ("b"), "Last predicate");
+}
+
+[Test]
+public void NSOrderedSet_Last_Empty_Throws ()
+{
+using var set = MakeOrderedSet ();
+Assert.Throws<InvalidOperationException> (() => set.Last ());
+}
+
+[Test]
+public void NSOrderedSet_LastOrDefault_Empty ()
+{
+using var set = MakeOrderedSet ();
+Assert.That (set.LastOrDefault (), Is.Null, "LastOrDefault empty");
+}
+
+[Test]
+public void NSOrderedSet_Single ()
+{
+using var set = MakeOrderedSet ("only");
+Assert.That (set.Single ().ToString (), Is.EqualTo ("only"), "Single");
+}
+
+[Test]
+public void NSOrderedSet_Single_Throws_OnMultiple ()
+{
+using var set = MakeOrderedSet ("a", "b");
+Assert.Throws<InvalidOperationException> (() => set.Single ());
+}
+
+[Test]
+public void NSOrderedSet_SingleOrDefault_Empty ()
+{
+using var set = MakeOrderedSet ();
+Assert.That (set.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
+}
+
+[Test]
+public void NSOrderedSet_SingleOrDefault_Predicate ()
+{
+using var set = MakeOrderedSet ("a", "b");
+Assert.That (set.SingleOrDefault (s => s.ToString () == "a")?.ToString (), Is.EqualTo ("a"), "SingleOrDefault predicate match");
+}
+
+[Test]
+public void NSOrderedSet_ElementAt ()
+{
+using var set = MakeOrderedSet ("a", "b", "c");
+Assert.That (set.ElementAt (1).ToString (), Is.EqualTo ("b"), "ElementAt 1");
+}
+
+[Test]
+public void NSOrderedSet_ElementAtOrDefault ()
+{
+using var set = MakeOrderedSet ("a");
+Assert.That (set.ElementAtOrDefault (0)?.ToString (), Is.EqualTo ("a"), "in range");
+Assert.That (set.ElementAtOrDefault (5), Is.Null, "out of range");
+}
+
+[Test]
+public void NSOrderedSet_Any ()
+{
+using var empty = MakeOrderedSet ();
+Assert.That (empty.Any (), Is.False, "Any empty");
+using var set = MakeOrderedSet ("a");
+Assert.That (set.Any (), Is.True, "Any non-empty");
+Assert.That (set.Any (s => s.ToString () == "a"), Is.True, "Any predicate true");
+Assert.That (set.Any (s => s.ToString () == "z"), Is.False, "Any predicate false");
+}
+
+[Test]
+public void NSOrderedSet_All ()
+{
+using var set = MakeOrderedSet ("ab", "abc");
+Assert.That (set.All (s => s.Length > 1), Is.True, "All true");
+Assert.That (set.All (s => s.Length > 2), Is.False, "All false");
+}
+
+[Test]
+public void NSOrderedSet_Count ()
+{
+using var set = MakeOrderedSet ("a", "b", "c");
+Assert.That (set.Count (), Is.EqualTo (3), "Count");
+Assert.That (set.Count (s => s.ToString () == "a"), Is.EqualTo (1), "Count predicate");
+}
+
+[Test]
+public void NSOrderedSet_LongCount ()
+{
+using var set = MakeOrderedSet ("a", "b");
+Assert.That (set.LongCount (), Is.EqualTo (2L), "LongCount");
+}
+
+[Test]
+public void NSOrderedSet_Where ()
+{
+using var set = MakeOrderedSet ("a", "bb", "ccc");
+var result = set.Where (s => s.Length > 1).ToList ();
+Assert.That (result.Count, Is.EqualTo (2), "Where count");
+}
+
+[Test]
+public void NSOrderedSet_Where_Index ()
+{
+using var set = MakeOrderedSet ("a", "b", "c");
+var result = set.Where ((s, i) => i % 2 == 0).ToList ();
+Assert.That (result.Count, Is.EqualTo (2), "Where index count");
+}
+
+[Test]
+public void NSOrderedSet_Select ()
+{
+using var set = MakeOrderedSet ("hello", "world");
+var lengths = set.Select (s => s.Length).ToList ();
+Assert.That (lengths [0], Is.EqualTo (5), "Select [0]");
+}
+
+[Test]
+public void NSOrderedSet_Select_Index ()
+{
+using var set = MakeOrderedSet ("a", "b");
+var indexed = set.Select ((s, i) => $"{i}:{s}").ToList ();
+Assert.That (indexed [0], Is.EqualTo ("0:a"), "Select index 0");
+}
+
+[Test]
+public void NSOrderedSet_OrderBy ()
+{
+using var set = MakeOrderedSet ("banana", "apple", "cherry");
+var sorted = set.OrderBy (s => s.ToString ()).ToList ();
+Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
+}
+
+[Test]
+public void NSOrderedSet_OrderByDescending ()
+{
+using var set = MakeOrderedSet ("banana", "apple", "cherry");
+var sorted = set.OrderByDescending (s => s.ToString ()).ToList ();
+Assert.That (sorted [0].ToString (), Is.EqualTo ("cherry"), "OrderByDesc first");
+}
+
+[Test]
+public void NSOrderedSet_Skip_Take ()
+{
+using var set = MakeOrderedSet ("a", "b", "c", "d");
+var sliced = set.Skip (1).Take (2).ToList ();
+Assert.That (sliced.Count, Is.EqualTo (2), "Skip/Take count");
+Assert.That (sliced [0].ToString (), Is.EqualTo ("b"), "Skip/Take [0]");
+}
+
+[Test]
+public void NSOrderedSet_SkipWhile_TakeWhile ()
+{
+using var set = MakeOrderedSet ("a", "b", "c");
+var skipped = set.SkipWhile (s => s.ToString () == "a").ToList ();
+Assert.That (skipped.Count, Is.EqualTo (2), "SkipWhile count");
+var taken = set.TakeWhile (s => s.ToString () != "c").ToList ();
+Assert.That (taken.Count, Is.EqualTo (2), "TakeWhile count");
+}
+
+[Test]
+public void NSOrderedSet_Distinct ()
+{
+using var set = MakeOrderedSet ("a", "b");
+var distinct = set.Distinct ().ToList ();
+Assert.That (distinct.Count, Is.EqualTo (2), "Distinct count");
+}
+
+[Test]
+public void NSOrderedSet_Reverse ()
+{
+using var set = MakeOrderedSet ("a", "b", "c");
+var reversed = set.Reverse ().ToList ();
+Assert.That (reversed [0].ToString (), Is.EqualTo ("c"), "Reverse [0]");
+Assert.That (reversed [2].ToString (), Is.EqualTo ("a"), "Reverse [2]");
+}
+
+[Test]
+public void NSOrderedSet_Concat ()
+{
+using var set = MakeOrderedSet ("a", "b");
+var all = set.Concat (new [] { S ("c") }).ToList ();
+Assert.That (all.Count, Is.EqualTo (3), "Concat count");
+}
+
+[Test]
+public void NSOrderedSet_ToList ()
+{
+using var set = MakeOrderedSet ("a", "b");
+var list = set.ToList ();
+Assert.That (list.Count, Is.EqualTo (2), "ToList count");
+}
+
+[Test]
+public void NSOrderedSet_ToArray ()
+{
+using var set = MakeOrderedSet ("a", "b");
+var arr = set.ToArray ();
+Assert.That (arr.Length, Is.EqualTo (2), "ToArray length");
+}
+
+[Test]
+public void NSOrderedSet_Aggregate ()
+{
+using var set = MakeOrderedSet ("a", "b", "c");
+var result = set.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
+Assert.That (result.ToString (), Is.EqualTo ("abc"), "Aggregate");
+}
+
+[Test]
+public void NSOrderedSet_Aggregate_Seed ()
+{
+using var set = MakeOrderedSet ("a", "b", "c");
+var result = set.Aggregate ("", (acc, s) => acc + s.ToString ());
+Assert.That (result, Is.EqualTo ("abc"), "Aggregate seed");
+}
+
+// ===== NSMutableOrderedSet<T> =====
+
+[Test]
+public void NSMutableOrderedSet_First ()
+{
+using var set = MakeMutableOrderedSet ("a", "b", "c");
+Assert.That (set.First ().ToString (), Is.EqualTo ("a"), "First");
+}
+
+[Test]
+public void NSMutableOrderedSet_First_Empty_Throws ()
+{
+using var set = MakeMutableOrderedSet ();
+Assert.Throws<InvalidOperationException> (() => set.First ());
+}
+
+[Test]
+public void NSMutableOrderedSet_FirstOrDefault_Empty ()
+{
+using var set = MakeMutableOrderedSet ();
+Assert.That (set.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
+}
+
+[Test]
+public void NSMutableOrderedSet_FirstOrDefault ()
+{
+using var set = MakeMutableOrderedSet ("x", "y");
+Assert.That (set.FirstOrDefault ()?.ToString (), Is.EqualTo ("x"), "FirstOrDefault");
+}
+
+[Test]
+public void NSMutableOrderedSet_FirstOrDefault_Predicate ()
+{
+using var set = MakeMutableOrderedSet ("a", "b", "c");
+Assert.That (set.FirstOrDefault (s => s.ToString () == "b")?.ToString (), Is.EqualTo ("b"), "FirstOrDefault predicate match");
+Assert.That (set.FirstOrDefault (s => s.ToString () == "z"), Is.Null, "FirstOrDefault predicate no match");
+}
+
+[Test]
+public void NSMutableOrderedSet_Last ()
+{
+using var set = MakeMutableOrderedSet ("a", "b", "c");
+Assert.That (set.Last ().ToString (), Is.EqualTo ("c"), "Last");
+}
+
+[Test]
+public void NSMutableOrderedSet_LastOrDefault_Empty ()
+{
+using var set = MakeMutableOrderedSet ();
+Assert.That (set.LastOrDefault (), Is.Null, "LastOrDefault empty");
+}
+
+[Test]
+public void NSMutableOrderedSet_Single ()
+{
+using var set = MakeMutableOrderedSet ("only");
+Assert.That (set.Single ().ToString (), Is.EqualTo ("only"), "Single");
+}
+
+[Test]
+public void NSMutableOrderedSet_Single_Throws_OnMultiple ()
+{
+using var set = MakeMutableOrderedSet ("a", "b");
+Assert.Throws<InvalidOperationException> (() => set.Single ());
+}
+
+[Test]
+public void NSMutableOrderedSet_SingleOrDefault_Empty ()
+{
+using var set = MakeMutableOrderedSet ();
+Assert.That (set.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
+}
+
+[Test]
+public void NSMutableOrderedSet_ElementAt ()
+{
+using var set = MakeMutableOrderedSet ("a", "b", "c");
+Assert.That (set.ElementAt (2).ToString (), Is.EqualTo ("c"), "ElementAt 2");
+}
+
+[Test]
+public void NSMutableOrderedSet_ElementAtOrDefault ()
+{
+using var set = MakeMutableOrderedSet ("a");
+Assert.That (set.ElementAtOrDefault (0)?.ToString (), Is.EqualTo ("a"), "in range");
+Assert.That (set.ElementAtOrDefault (5), Is.Null, "out of range");
+}
+
+[Test]
+public void NSMutableOrderedSet_Any ()
+{
+using var empty = MakeMutableOrderedSet ();
+Assert.That (empty.Any (), Is.False, "Any empty");
+using var set = MakeMutableOrderedSet ("a");
+Assert.That (set.Any (), Is.True, "Any non-empty");
+}
+
+[Test]
+public void NSMutableOrderedSet_All ()
+{
+using var set = MakeMutableOrderedSet ("ab", "abc");
+Assert.That (set.All (s => s.Length > 1), Is.True, "All true");
+}
+
+[Test]
+public void NSMutableOrderedSet_Count ()
+{
+using var set = MakeMutableOrderedSet ("a", "b", "c");
+Assert.That (set.Count (), Is.EqualTo (3), "Count");
+Assert.That (set.Count (s => s.ToString () == "a"), Is.EqualTo (1), "Count predicate");
+}
+
+[Test]
+public void NSMutableOrderedSet_LongCount ()
+{
+using var set = MakeMutableOrderedSet ("a", "b");
+Assert.That (set.LongCount (), Is.EqualTo (2L), "LongCount");
+}
+
+[Test]
+public void NSMutableOrderedSet_Where ()
+{
+using var set = MakeMutableOrderedSet ("a", "bb", "ccc");
+var result = set.Where (s => s.Length > 1).ToList ();
+Assert.That (result.Count, Is.EqualTo (2), "Where count");
+}
+
+[Test]
+public void NSMutableOrderedSet_Select ()
+{
+using var set = MakeMutableOrderedSet ("hello", "world");
+var lengths = set.Select (s => s.Length).ToList ();
+Assert.That (lengths [0], Is.EqualTo (5), "Select [0]");
+}
+
+[Test]
+public void NSMutableOrderedSet_OrderBy ()
+{
+using var set = MakeMutableOrderedSet ("banana", "apple", "cherry");
+var sorted = set.OrderBy (s => s.ToString ()).ToList ();
+Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
+}
+
+[Test]
+public void NSMutableOrderedSet_OrderByDescending ()
+{
+using var set = MakeMutableOrderedSet ("banana", "apple", "cherry");
+var sorted = set.OrderByDescending (s => s.ToString ()).ToList ();
+Assert.That (sorted [0].ToString (), Is.EqualTo ("cherry"), "OrderByDesc first");
+}
+
+[Test]
+public void NSMutableOrderedSet_Skip_Take ()
+{
+using var set = MakeMutableOrderedSet ("a", "b", "c", "d");
+var sliced = set.Skip (1).Take (2).ToList ();
+Assert.That (sliced.Count, Is.EqualTo (2), "Skip/Take count");
+Assert.That (sliced [0].ToString (), Is.EqualTo ("b"), "Skip/Take [0]");
+}
+
+[Test]
+public void NSMutableOrderedSet_SkipWhile_TakeWhile ()
+{
+using var set = MakeMutableOrderedSet ("a", "b", "c");
+var skipped = set.SkipWhile (s => s.ToString () == "a").ToList ();
+Assert.That (skipped.Count, Is.EqualTo (2), "SkipWhile count");
+var taken = set.TakeWhile (s => s.ToString () != "c").ToList ();
+Assert.That (taken.Count, Is.EqualTo (2), "TakeWhile count");
+}
+
+[Test]
+public void NSMutableOrderedSet_Distinct ()
+{
+using var set = MakeMutableOrderedSet ("a", "b");
+var distinct = set.Distinct ().ToList ();
+Assert.That (distinct.Count, Is.EqualTo (2), "Distinct count");
+}
+
+[Test]
+public void NSMutableOrderedSet_Reverse ()
+{
+using var set = MakeMutableOrderedSet ("a", "b", "c");
+var reversed = set.Reverse ().ToList ();
+Assert.That (reversed [0].ToString (), Is.EqualTo ("c"), "Reverse [0]");
+Assert.That (reversed [2].ToString (), Is.EqualTo ("a"), "Reverse [2]");
+}
+
+[Test]
+public void NSMutableOrderedSet_Concat ()
+{
+using var set = MakeMutableOrderedSet ("a", "b");
+var all = set.Concat (new [] { S ("c") }).ToList ();
+Assert.That (all.Count, Is.EqualTo (3), "Concat count");
+}
+
+[Test]
+public void NSMutableOrderedSet_ToList ()
+{
+using var set = MakeMutableOrderedSet ("a", "b");
+var list = set.ToList ();
+Assert.That (list.Count, Is.EqualTo (2), "ToList count");
+}
+
+[Test]
+public void NSMutableOrderedSet_ToArray ()
+{
+using var set = MakeMutableOrderedSet ("a", "b");
+var arr = set.ToArray ();
+Assert.That (arr.Length, Is.EqualTo (2), "ToArray length");
+}
+
+[Test]
+public void NSMutableOrderedSet_Aggregate ()
+{
+using var set = MakeMutableOrderedSet ("a", "b", "c");
+var result = set.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
+Assert.That (result.ToString (), Is.EqualTo ("abc"), "Aggregate");
+}
+
+[Test]
+public void NSMutableOrderedSet_Aggregate_Seed ()
+{
+using var set = MakeMutableOrderedSet ("a", "b", "c");
+var result = set.Aggregate ("", (acc, s) => acc + s.ToString ());
+Assert.That (result, Is.EqualTo ("abc"), "Aggregate seed");
+}
+}
+}

From 14c2c6d8b2b805d373c55db8a758d350769442c9 Mon Sep 17 00:00:00 2001
From: Rolf Bjarne Kvinge <rolf@xamarin.com>
Date: Wed, 27 May 2026 17:30:00 +0200
Subject: [PATCH 5/6] Fix build: use ObjCRuntime.INativeObject in LINQ
 extension constraints

INativeObject is defined in the ObjCRuntime namespace, not Foundation.
The generic type constraints on all 228 extension methods were referencing
Foundation.INativeObject which doesn't exist, causing CS0234/CS0311 errors.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 src/Foundation/NSCollectionLinqExtensions.cs | 456 +++++++++----------
 1 file changed, 228 insertions(+), 228 deletions(-)

diff --git a/src/Foundation/NSCollectionLinqExtensions.cs b/src/Foundation/NSCollectionLinqExtensions.cs
index fa636d2ae0a0..b60d8920dd77 100644
--- a/src/Foundation/NSCollectionLinqExtensions.cs
+++ b/src/Foundation/NSCollectionLinqExtensions.cs
@@ -11,7 +11,7 @@ public static class NSCollectionLinqExtensions {
 		/// <returns>The first element in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey First<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey First<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.First ((IEnumerable<TKey>) source);
@@ -24,7 +24,7 @@ public static TKey First<TKey> (this Foundation.NSSet<TKey> source) where TKey :
 		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey First<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey First<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -36,7 +36,7 @@ public static TKey First<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, b
 		/// <param name="source">The source collection.</param>
 		/// <returns>The first element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
@@ -48,7 +48,7 @@ public static TKey First<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, b
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -61,7 +61,7 @@ public static TKey First<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, b
 		/// <returns>The last element in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey Last<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey Last<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Last ((IEnumerable<TKey>) source);
@@ -74,7 +74,7 @@ public static TKey Last<TKey> (this Foundation.NSSet<TKey> source) where TKey :
 		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey Last<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey Last<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -86,7 +86,7 @@ public static TKey Last<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bo
 		/// <param name="source">The source collection.</param>
 		/// <returns>The last element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? LastOrDefault<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source);
@@ -98,7 +98,7 @@ public static TKey Last<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bo
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static TKey? LastOrDefault<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -111,7 +111,7 @@ public static TKey Last<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bo
 		/// <returns>The single element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty or contains more than one element.</exception>
-		public static TKey Single<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey Single<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Single ((IEnumerable<TKey>) source);
@@ -124,7 +124,7 @@ public static TKey Single<TKey> (this Foundation.NSSet<TKey> source) where TKey
 		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element or more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey Single<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey Single<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -137,7 +137,7 @@ public static TKey Single<TKey> (this Foundation.NSSet<TKey> source, Func<TKey,
 		/// <returns>The single element of <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> contains more than one element.</exception>
-		public static TKey? SingleOrDefault<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source);
@@ -150,7 +150,7 @@ public static TKey Single<TKey> (this Foundation.NSSet<TKey> source, Func<TKey,
 		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey? SingleOrDefault<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -164,7 +164,7 @@ public static TKey Single<TKey> (this Foundation.NSSet<TKey> source, Func<TKey,
 		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="index"/> is less than 0 or greater than or equal to the number of elements in <paramref name="source"/>.</exception>
-		public static TKey ElementAt<TKey> (this Foundation.NSSet<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		public static TKey ElementAt<TKey> (this Foundation.NSSet<TKey> source, int index) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ElementAt ((IEnumerable<TKey>) source, index);
@@ -176,7 +176,7 @@ public static TKey ElementAt<TKey> (this Foundation.NSSet<TKey> source, int inde
 		/// <param name="index">The zero-based index of the element to retrieve.</param>
 		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>, or <see langword="null"/> if the index is out of range.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSSet<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSSet<TKey> source, int index) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ElementAtOrDefault ((IEnumerable<TKey>) source, index);
@@ -187,7 +187,7 @@ public static TKey ElementAt<TKey> (this Foundation.NSSet<TKey> source, int inde
 		/// <param name="source">The source collection.</param>
 		/// <returns><see langword="true"/> if <paramref name="source"/> contains any elements; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static bool Any<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static bool Any<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Any ((IEnumerable<TKey>) source);
@@ -199,7 +199,7 @@ public static bool Any<TKey> (this Foundation.NSSet<TKey> source) where TKey : c
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns><see langword="true"/> if any element in <paramref name="source"/> passes the test in <paramref name="predicate"/>; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static bool Any<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static bool Any<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -212,7 +212,7 @@ public static bool Any<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, boo
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns><see langword="true"/> if every element in <paramref name="source"/> passes the test in <paramref name="predicate"/>, or if the collection is empty; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static bool All<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static bool All<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -224,7 +224,7 @@ public static bool All<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, boo
 		/// <param name="source">The source collection.</param>
 		/// <returns>The number of elements in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static int Count<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static int Count<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Count ((IEnumerable<TKey>) source);
@@ -236,7 +236,7 @@ public static int Count<TKey> (this Foundation.NSSet<TKey> source) where TKey :
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static int Count<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static int Count<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -248,7 +248,7 @@ public static int Count<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bo
 		/// <param name="source">The source collection.</param>
 		/// <returns>The number of elements in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static long LongCount<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static long LongCount<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.LongCount ((IEnumerable<TKey>) source);
@@ -260,7 +260,7 @@ public static long LongCount<TKey> (this Foundation.NSSet<TKey> source) where TK
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static long LongCount<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static long LongCount<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -273,7 +273,7 @@ public static long LongCount<TKey> (this Foundation.NSSet<TKey> source, Func<TKe
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -286,7 +286,7 @@ public static IEnumerable<TKey> Where<TKey> (this Foundation.NSSet<TKey> source,
 		/// <param name="predicate">A function to test each element; the second parameter represents the zero-based index of the element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -300,7 +300,7 @@ public static IEnumerable<TKey> Where<TKey> (this Foundation.NSSet<TKey> source,
 		/// <param name="selector">A transform function to apply to each element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSSet<TKey> source, Func<TKey, TResult> selector) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSSet<TKey> source, Func<TKey, TResult> selector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (selector);
@@ -314,7 +314,7 @@ public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSSet<
 		/// <param name="selector">A transform function to apply to each element; the second parameter represents the zero-based index of the element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSSet<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSSet<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (selector);
@@ -328,7 +328,7 @@ public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSSet<
 		/// <param name="keySelector">A function to extract a key from an element.</param>
 		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted according to a key.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
-		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (keySelector);
@@ -342,7 +342,7 @@ public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation
 		/// <param name="keySelector">A function to extract a key from an element.</param>
 		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted in descending order according to a key.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
-		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (keySelector);
@@ -355,7 +355,7 @@ public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this
 		/// <param name="count">The number of elements to skip before returning the remaining elements.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements after the skipped ones.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSSet<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSSet<TKey> source, int count) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Skip ((IEnumerable<TKey>) source, count);
@@ -367,7 +367,7 @@ public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSSet<TKey> source,
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the elements starting at the first element that does not satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -380,7 +380,7 @@ public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSSet<TKey> sou
 		/// <param name="count">The number of elements to return.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the specified number of elements from the start of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSSet<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSSet<TKey> source, int count) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Take ((IEnumerable<TKey>) source, count);
@@ -392,7 +392,7 @@ public static IEnumerable<TKey> Take<TKey> (this Foundation.NSSet<TKey> source,
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> as long as the condition is true.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -404,7 +404,7 @@ public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSSet<TKey> sou
 		/// <param name="source">The source collection.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains distinct elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Distinct ((IEnumerable<TKey>) source);
@@ -415,7 +415,7 @@ public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSSet<TKey> sour
 		/// <param name="source">The source collection.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements correspond to those of <paramref name="source"/> in reverse order.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Reverse ((IEnumerable<TKey>) source);
@@ -427,7 +427,7 @@ public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSSet<TKey> sourc
 		/// <param name="second">The sequence to concatenate to <paramref name="source"/>.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the concatenated elements of the two sequences.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="second"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSSet<TKey> source, IEnumerable<TKey> second) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSSet<TKey> source, IEnumerable<TKey> second) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (second);
@@ -439,7 +439,7 @@ public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSSet<TKey> source
 		/// <param name="source">The source collection.</param>
 		/// <returns>A <see cref="List{T}"/> that contains elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static List<TKey> ToList<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static List<TKey> ToList<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ToList ((IEnumerable<TKey>) source);
@@ -450,7 +450,7 @@ public static List<TKey> ToList<TKey> (this Foundation.NSSet<TKey> source) where
 		/// <param name="source">The source collection.</param>
 		/// <returns>An array that contains elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey [] ToArray<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey [] ToArray<TKey> (this Foundation.NSSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ToArray ((IEnumerable<TKey>) source);
@@ -463,7 +463,7 @@ public static TKey [] ToArray<TKey> (this Foundation.NSSet<TKey> source) where T
 		/// <returns>The final accumulator value.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey Aggregate<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, Foundation.INativeObject
+		public static TKey Aggregate<TKey> (this Foundation.NSSet<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (func);
@@ -478,7 +478,7 @@ public static TKey Aggregate<TKey> (this Foundation.NSSet<TKey> source, Func<TKe
 		/// <param name="func">An accumulator function to be invoked on each element.</param>
 		/// <returns>The final accumulator value.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
-		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSSet<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, Foundation.INativeObject
+		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSSet<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (func);
@@ -492,7 +492,7 @@ public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSSet<TK
 		/// <returns>The first element in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey First<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey First<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.First ((IEnumerable<TKey>) source);
@@ -505,7 +505,7 @@ public static TKey First<TKey> (this Foundation.NSMutableSet<TKey> source) where
 		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey First<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey First<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -517,7 +517,7 @@ public static TKey First<TKey> (this Foundation.NSMutableSet<TKey> source, Func<
 		/// <param name="source">The source collection.</param>
 		/// <returns>The first element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
@@ -529,7 +529,7 @@ public static TKey First<TKey> (this Foundation.NSMutableSet<TKey> source, Func<
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -542,7 +542,7 @@ public static TKey First<TKey> (this Foundation.NSMutableSet<TKey> source, Func<
 		/// <returns>The last element in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey Last<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey Last<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Last ((IEnumerable<TKey>) source);
@@ -555,7 +555,7 @@ public static TKey Last<TKey> (this Foundation.NSMutableSet<TKey> source) where
 		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey Last<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey Last<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -567,7 +567,7 @@ public static TKey Last<TKey> (this Foundation.NSMutableSet<TKey> source, Func<T
 		/// <param name="source">The source collection.</param>
 		/// <returns>The last element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source);
@@ -579,7 +579,7 @@ public static TKey Last<TKey> (this Foundation.NSMutableSet<TKey> source, Func<T
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -592,7 +592,7 @@ public static TKey Last<TKey> (this Foundation.NSMutableSet<TKey> source, Func<T
 		/// <returns>The single element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty or contains more than one element.</exception>
-		public static TKey Single<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey Single<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Single ((IEnumerable<TKey>) source);
@@ -605,7 +605,7 @@ public static TKey Single<TKey> (this Foundation.NSMutableSet<TKey> source) wher
 		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element or more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey Single<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey Single<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -618,7 +618,7 @@ public static TKey Single<TKey> (this Foundation.NSMutableSet<TKey> source, Func
 		/// <returns>The single element of <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> contains more than one element.</exception>
-		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source);
@@ -631,7 +631,7 @@ public static TKey Single<TKey> (this Foundation.NSMutableSet<TKey> source, Func
 		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -645,7 +645,7 @@ public static TKey Single<TKey> (this Foundation.NSMutableSet<TKey> source, Func
 		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="index"/> is less than 0 or greater than or equal to the number of elements in <paramref name="source"/>.</exception>
-		public static TKey ElementAt<TKey> (this Foundation.NSMutableSet<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		public static TKey ElementAt<TKey> (this Foundation.NSMutableSet<TKey> source, int index) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ElementAt ((IEnumerable<TKey>) source, index);
@@ -657,7 +657,7 @@ public static TKey ElementAt<TKey> (this Foundation.NSMutableSet<TKey> source, i
 		/// <param name="index">The zero-based index of the element to retrieve.</param>
 		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>, or <see langword="null"/> if the index is out of range.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSMutableSet<TKey> source, int index) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ElementAtOrDefault ((IEnumerable<TKey>) source, index);
@@ -668,7 +668,7 @@ public static TKey ElementAt<TKey> (this Foundation.NSMutableSet<TKey> source, i
 		/// <param name="source">The source collection.</param>
 		/// <returns><see langword="true"/> if <paramref name="source"/> contains any elements; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static bool Any<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static bool Any<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Any ((IEnumerable<TKey>) source);
@@ -680,7 +680,7 @@ public static bool Any<TKey> (this Foundation.NSMutableSet<TKey> source) where T
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns><see langword="true"/> if any element in <paramref name="source"/> passes the test in <paramref name="predicate"/>; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static bool Any<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static bool Any<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -693,7 +693,7 @@ public static bool Any<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TK
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns><see langword="true"/> if every element in <paramref name="source"/> passes the test in <paramref name="predicate"/>, or if the collection is empty; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static bool All<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static bool All<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -705,7 +705,7 @@ public static bool All<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TK
 		/// <param name="source">The source collection.</param>
 		/// <returns>The number of elements in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static int Count<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static int Count<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Count ((IEnumerable<TKey>) source);
@@ -717,7 +717,7 @@ public static int Count<TKey> (this Foundation.NSMutableSet<TKey> source) where
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static int Count<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static int Count<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -729,7 +729,7 @@ public static int Count<TKey> (this Foundation.NSMutableSet<TKey> source, Func<T
 		/// <param name="source">The source collection.</param>
 		/// <returns>The number of elements in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static long LongCount<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static long LongCount<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.LongCount ((IEnumerable<TKey>) source);
@@ -741,7 +741,7 @@ public static long LongCount<TKey> (this Foundation.NSMutableSet<TKey> source) w
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static long LongCount<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static long LongCount<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -754,7 +754,7 @@ public static long LongCount<TKey> (this Foundation.NSMutableSet<TKey> source, F
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -767,7 +767,7 @@ public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableSet<TKey>
 		/// <param name="predicate">A function to test each element; the second parameter represents the zero-based index of the element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -781,7 +781,7 @@ public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableSet<TKey>
 		/// <param name="selector">A transform function to apply to each element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableSet<TKey> source, Func<TKey, TResult> selector) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableSet<TKey> source, Func<TKey, TResult> selector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (selector);
@@ -795,7 +795,7 @@ public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMuta
 		/// <param name="selector">A transform function to apply to each element; the second parameter represents the zero-based index of the element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableSet<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableSet<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (selector);
@@ -809,7 +809,7 @@ public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMuta
 		/// <param name="keySelector">A function to extract a key from an element.</param>
 		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted according to a key.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
-		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (keySelector);
@@ -823,7 +823,7 @@ public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation
 		/// <param name="keySelector">A function to extract a key from an element.</param>
 		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted in descending order according to a key.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
-		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (keySelector);
@@ -836,7 +836,7 @@ public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this
 		/// <param name="count">The number of elements to skip before returning the remaining elements.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements after the skipped ones.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSMutableSet<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSMutableSet<TKey> source, int count) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Skip ((IEnumerable<TKey>) source, count);
@@ -848,7 +848,7 @@ public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSMutableSet<TKey> s
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the elements starting at the first element that does not satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -861,7 +861,7 @@ public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSMutableSet<TK
 		/// <param name="count">The number of elements to return.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the specified number of elements from the start of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSMutableSet<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSMutableSet<TKey> source, int count) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Take ((IEnumerable<TKey>) source, count);
@@ -873,7 +873,7 @@ public static IEnumerable<TKey> Take<TKey> (this Foundation.NSMutableSet<TKey> s
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> as long as the condition is true.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -885,7 +885,7 @@ public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSMutableSet<TK
 		/// <param name="source">The source collection.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains distinct elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Distinct ((IEnumerable<TKey>) source);
@@ -896,7 +896,7 @@ public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSMutableSet<TKe
 		/// <param name="source">The source collection.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements correspond to those of <paramref name="source"/> in reverse order.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Reverse ((IEnumerable<TKey>) source);
@@ -908,7 +908,7 @@ public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSMutableSet<TKey
 		/// <param name="second">The sequence to concatenate to <paramref name="source"/>.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the concatenated elements of the two sequences.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="second"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSMutableSet<TKey> source, IEnumerable<TKey> second) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSMutableSet<TKey> source, IEnumerable<TKey> second) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (second);
@@ -920,7 +920,7 @@ public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSMutableSet<TKey>
 		/// <param name="source">The source collection.</param>
 		/// <returns>A <see cref="List{T}"/> that contains elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static List<TKey> ToList<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static List<TKey> ToList<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ToList ((IEnumerable<TKey>) source);
@@ -931,7 +931,7 @@ public static List<TKey> ToList<TKey> (this Foundation.NSMutableSet<TKey> source
 		/// <param name="source">The source collection.</param>
 		/// <returns>An array that contains elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey [] ToArray<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey [] ToArray<TKey> (this Foundation.NSMutableSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ToArray ((IEnumerable<TKey>) source);
@@ -944,7 +944,7 @@ public static TKey [] ToArray<TKey> (this Foundation.NSMutableSet<TKey> source)
 		/// <returns>The final accumulator value.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey Aggregate<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, Foundation.INativeObject
+		public static TKey Aggregate<TKey> (this Foundation.NSMutableSet<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (func);
@@ -959,7 +959,7 @@ public static TKey Aggregate<TKey> (this Foundation.NSMutableSet<TKey> source, F
 		/// <param name="func">An accumulator function to be invoked on each element.</param>
 		/// <returns>The final accumulator value.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
-		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSMutableSet<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, Foundation.INativeObject
+		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSMutableSet<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (func);
@@ -973,7 +973,7 @@ public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSMutabl
 		/// <returns>The first element in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey First<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey First<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.First ((IEnumerable<TKey>) source);
@@ -986,7 +986,7 @@ public static TKey First<TKey> (this Foundation.NSArray<TKey> source) where TKey
 		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey First<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey First<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -998,7 +998,7 @@ public static TKey First<TKey> (this Foundation.NSArray<TKey> source, Func<TKey,
 		/// <param name="source">The source collection.</param>
 		/// <returns>The first element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
@@ -1010,7 +1010,7 @@ public static TKey First<TKey> (this Foundation.NSArray<TKey> source, Func<TKey,
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1023,7 +1023,7 @@ public static TKey First<TKey> (this Foundation.NSArray<TKey> source, Func<TKey,
 		/// <returns>The last element in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey Last<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey Last<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Last ((IEnumerable<TKey>) source);
@@ -1036,7 +1036,7 @@ public static TKey Last<TKey> (this Foundation.NSArray<TKey> source) where TKey
 		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey Last<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey Last<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1048,7 +1048,7 @@ public static TKey Last<TKey> (this Foundation.NSArray<TKey> source, Func<TKey,
 		/// <param name="source">The source collection.</param>
 		/// <returns>The last element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? LastOrDefault<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source);
@@ -1060,7 +1060,7 @@ public static TKey Last<TKey> (this Foundation.NSArray<TKey> source, Func<TKey,
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static TKey? LastOrDefault<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1073,7 +1073,7 @@ public static TKey Last<TKey> (this Foundation.NSArray<TKey> source, Func<TKey,
 		/// <returns>The single element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty or contains more than one element.</exception>
-		public static TKey Single<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey Single<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Single ((IEnumerable<TKey>) source);
@@ -1086,7 +1086,7 @@ public static TKey Single<TKey> (this Foundation.NSArray<TKey> source) where TKe
 		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element or more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey Single<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey Single<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1099,7 +1099,7 @@ public static TKey Single<TKey> (this Foundation.NSArray<TKey> source, Func<TKey
 		/// <returns>The single element of <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> contains more than one element.</exception>
-		public static TKey? SingleOrDefault<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source);
@@ -1112,7 +1112,7 @@ public static TKey Single<TKey> (this Foundation.NSArray<TKey> source, Func<TKey
 		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey? SingleOrDefault<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1126,7 +1126,7 @@ public static TKey Single<TKey> (this Foundation.NSArray<TKey> source, Func<TKey
 		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="index"/> is less than 0 or greater than or equal to the number of elements in <paramref name="source"/>.</exception>
-		public static TKey ElementAt<TKey> (this Foundation.NSArray<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		public static TKey ElementAt<TKey> (this Foundation.NSArray<TKey> source, int index) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ElementAt ((IEnumerable<TKey>) source, index);
@@ -1138,7 +1138,7 @@ public static TKey ElementAt<TKey> (this Foundation.NSArray<TKey> source, int in
 		/// <param name="index">The zero-based index of the element to retrieve.</param>
 		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>, or <see langword="null"/> if the index is out of range.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSArray<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSArray<TKey> source, int index) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ElementAtOrDefault ((IEnumerable<TKey>) source, index);
@@ -1149,7 +1149,7 @@ public static TKey ElementAt<TKey> (this Foundation.NSArray<TKey> source, int in
 		/// <param name="source">The source collection.</param>
 		/// <returns><see langword="true"/> if <paramref name="source"/> contains any elements; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static bool Any<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static bool Any<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Any ((IEnumerable<TKey>) source);
@@ -1161,7 +1161,7 @@ public static bool Any<TKey> (this Foundation.NSArray<TKey> source) where TKey :
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns><see langword="true"/> if any element in <paramref name="source"/> passes the test in <paramref name="predicate"/>; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static bool Any<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static bool Any<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1174,7 +1174,7 @@ public static bool Any<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, b
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns><see langword="true"/> if every element in <paramref name="source"/> passes the test in <paramref name="predicate"/>, or if the collection is empty; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static bool All<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static bool All<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1186,7 +1186,7 @@ public static bool All<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, b
 		/// <param name="source">The source collection.</param>
 		/// <returns>The number of elements in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static int Count<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static int Count<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Count ((IEnumerable<TKey>) source);
@@ -1198,7 +1198,7 @@ public static int Count<TKey> (this Foundation.NSArray<TKey> source) where TKey
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static int Count<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static int Count<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1210,7 +1210,7 @@ public static int Count<TKey> (this Foundation.NSArray<TKey> source, Func<TKey,
 		/// <param name="source">The source collection.</param>
 		/// <returns>The number of elements in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static long LongCount<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static long LongCount<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.LongCount ((IEnumerable<TKey>) source);
@@ -1222,7 +1222,7 @@ public static long LongCount<TKey> (this Foundation.NSArray<TKey> source) where
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static long LongCount<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static long LongCount<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1235,7 +1235,7 @@ public static long LongCount<TKey> (this Foundation.NSArray<TKey> source, Func<T
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1248,7 +1248,7 @@ public static IEnumerable<TKey> Where<TKey> (this Foundation.NSArray<TKey> sourc
 		/// <param name="predicate">A function to test each element; the second parameter represents the zero-based index of the element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1262,7 +1262,7 @@ public static IEnumerable<TKey> Where<TKey> (this Foundation.NSArray<TKey> sourc
 		/// <param name="selector">A transform function to apply to each element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSArray<TKey> source, Func<TKey, TResult> selector) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSArray<TKey> source, Func<TKey, TResult> selector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (selector);
@@ -1276,7 +1276,7 @@ public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSArra
 		/// <param name="selector">A transform function to apply to each element; the second parameter represents the zero-based index of the element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSArray<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSArray<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (selector);
@@ -1290,7 +1290,7 @@ public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSArra
 		/// <param name="keySelector">A function to extract a key from an element.</param>
 		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted according to a key.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
-		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSArray<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSArray<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (keySelector);
@@ -1304,7 +1304,7 @@ public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation
 		/// <param name="keySelector">A function to extract a key from an element.</param>
 		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted in descending order according to a key.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
-		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSArray<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSArray<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (keySelector);
@@ -1317,7 +1317,7 @@ public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this
 		/// <param name="count">The number of elements to skip before returning the remaining elements.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements after the skipped ones.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSArray<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSArray<TKey> source, int count) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Skip ((IEnumerable<TKey>) source, count);
@@ -1329,7 +1329,7 @@ public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSArray<TKey> source
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the elements starting at the first element that does not satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1342,7 +1342,7 @@ public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSArray<TKey> s
 		/// <param name="count">The number of elements to return.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the specified number of elements from the start of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSArray<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSArray<TKey> source, int count) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Take ((IEnumerable<TKey>) source, count);
@@ -1354,7 +1354,7 @@ public static IEnumerable<TKey> Take<TKey> (this Foundation.NSArray<TKey> source
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> as long as the condition is true.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1366,7 +1366,7 @@ public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSArray<TKey> s
 		/// <param name="source">The source collection.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains distinct elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Distinct ((IEnumerable<TKey>) source);
@@ -1377,7 +1377,7 @@ public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSArray<TKey> so
 		/// <param name="source">The source collection.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements correspond to those of <paramref name="source"/> in reverse order.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Reverse ((IEnumerable<TKey>) source);
@@ -1389,7 +1389,7 @@ public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSArray<TKey> sou
 		/// <param name="second">The sequence to concatenate to <paramref name="source"/>.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the concatenated elements of the two sequences.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="second"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSArray<TKey> source, IEnumerable<TKey> second) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSArray<TKey> source, IEnumerable<TKey> second) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (second);
@@ -1401,7 +1401,7 @@ public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSArray<TKey> sour
 		/// <param name="source">The source collection.</param>
 		/// <returns>A <see cref="List{T}"/> that contains elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static List<TKey> ToList<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static List<TKey> ToList<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ToList ((IEnumerable<TKey>) source);
@@ -1412,7 +1412,7 @@ public static List<TKey> ToList<TKey> (this Foundation.NSArray<TKey> source) whe
 		/// <param name="source">The source collection.</param>
 		/// <returns>An array that contains elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey [] ToArray<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey [] ToArray<TKey> (this Foundation.NSArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ToArray ((IEnumerable<TKey>) source);
@@ -1425,7 +1425,7 @@ public static TKey [] ToArray<TKey> (this Foundation.NSArray<TKey> source) where
 		/// <returns>The final accumulator value.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey Aggregate<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, Foundation.INativeObject
+		public static TKey Aggregate<TKey> (this Foundation.NSArray<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (func);
@@ -1440,7 +1440,7 @@ public static TKey Aggregate<TKey> (this Foundation.NSArray<TKey> source, Func<T
 		/// <param name="func">An accumulator function to be invoked on each element.</param>
 		/// <returns>The final accumulator value.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
-		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSArray<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, Foundation.INativeObject
+		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSArray<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (func);
@@ -1454,7 +1454,7 @@ public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSArray<
 		/// <returns>The first element in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey First<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey First<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.First ((IEnumerable<TKey>) source);
@@ -1467,7 +1467,7 @@ public static TKey First<TKey> (this Foundation.NSMutableArray<TKey> source) whe
 		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey First<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey First<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1479,7 +1479,7 @@ public static TKey First<TKey> (this Foundation.NSMutableArray<TKey> source, Fun
 		/// <param name="source">The source collection.</param>
 		/// <returns>The first element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
@@ -1491,7 +1491,7 @@ public static TKey First<TKey> (this Foundation.NSMutableArray<TKey> source, Fun
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1504,7 +1504,7 @@ public static TKey First<TKey> (this Foundation.NSMutableArray<TKey> source, Fun
 		/// <returns>The last element in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey Last<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey Last<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Last ((IEnumerable<TKey>) source);
@@ -1517,7 +1517,7 @@ public static TKey Last<TKey> (this Foundation.NSMutableArray<TKey> source) wher
 		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey Last<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey Last<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1529,7 +1529,7 @@ public static TKey Last<TKey> (this Foundation.NSMutableArray<TKey> source, Func
 		/// <param name="source">The source collection.</param>
 		/// <returns>The last element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source);
@@ -1541,7 +1541,7 @@ public static TKey Last<TKey> (this Foundation.NSMutableArray<TKey> source, Func
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1554,7 +1554,7 @@ public static TKey Last<TKey> (this Foundation.NSMutableArray<TKey> source, Func
 		/// <returns>The single element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty or contains more than one element.</exception>
-		public static TKey Single<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey Single<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Single ((IEnumerable<TKey>) source);
@@ -1567,7 +1567,7 @@ public static TKey Single<TKey> (this Foundation.NSMutableArray<TKey> source) wh
 		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element or more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey Single<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey Single<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1580,7 +1580,7 @@ public static TKey Single<TKey> (this Foundation.NSMutableArray<TKey> source, Fu
 		/// <returns>The single element of <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> contains more than one element.</exception>
-		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source);
@@ -1593,7 +1593,7 @@ public static TKey Single<TKey> (this Foundation.NSMutableArray<TKey> source, Fu
 		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1607,7 +1607,7 @@ public static TKey Single<TKey> (this Foundation.NSMutableArray<TKey> source, Fu
 		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="index"/> is less than 0 or greater than or equal to the number of elements in <paramref name="source"/>.</exception>
-		public static TKey ElementAt<TKey> (this Foundation.NSMutableArray<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		public static TKey ElementAt<TKey> (this Foundation.NSMutableArray<TKey> source, int index) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ElementAt ((IEnumerable<TKey>) source, index);
@@ -1619,7 +1619,7 @@ public static TKey ElementAt<TKey> (this Foundation.NSMutableArray<TKey> source,
 		/// <param name="index">The zero-based index of the element to retrieve.</param>
 		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>, or <see langword="null"/> if the index is out of range.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSMutableArray<TKey> source, int index) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ElementAtOrDefault ((IEnumerable<TKey>) source, index);
@@ -1630,7 +1630,7 @@ public static TKey ElementAt<TKey> (this Foundation.NSMutableArray<TKey> source,
 		/// <param name="source">The source collection.</param>
 		/// <returns><see langword="true"/> if <paramref name="source"/> contains any elements; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static bool Any<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static bool Any<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Any ((IEnumerable<TKey>) source);
@@ -1642,7 +1642,7 @@ public static bool Any<TKey> (this Foundation.NSMutableArray<TKey> source) where
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns><see langword="true"/> if any element in <paramref name="source"/> passes the test in <paramref name="predicate"/>; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static bool Any<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static bool Any<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1655,7 +1655,7 @@ public static bool Any<TKey> (this Foundation.NSMutableArray<TKey> source, Func<
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns><see langword="true"/> if every element in <paramref name="source"/> passes the test in <paramref name="predicate"/>, or if the collection is empty; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static bool All<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static bool All<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1667,7 +1667,7 @@ public static bool All<TKey> (this Foundation.NSMutableArray<TKey> source, Func<
 		/// <param name="source">The source collection.</param>
 		/// <returns>The number of elements in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static int Count<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static int Count<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Count ((IEnumerable<TKey>) source);
@@ -1679,7 +1679,7 @@ public static int Count<TKey> (this Foundation.NSMutableArray<TKey> source) wher
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static int Count<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static int Count<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1691,7 +1691,7 @@ public static int Count<TKey> (this Foundation.NSMutableArray<TKey> source, Func
 		/// <param name="source">The source collection.</param>
 		/// <returns>The number of elements in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static long LongCount<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static long LongCount<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.LongCount ((IEnumerable<TKey>) source);
@@ -1703,7 +1703,7 @@ public static long LongCount<TKey> (this Foundation.NSMutableArray<TKey> source)
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static long LongCount<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static long LongCount<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1716,7 +1716,7 @@ public static long LongCount<TKey> (this Foundation.NSMutableArray<TKey> source,
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1729,7 +1729,7 @@ public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableArray<TKey
 		/// <param name="predicate">A function to test each element; the second parameter represents the zero-based index of the element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1743,7 +1743,7 @@ public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableArray<TKey
 		/// <param name="selector">A transform function to apply to each element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableArray<TKey> source, Func<TKey, TResult> selector) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableArray<TKey> source, Func<TKey, TResult> selector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (selector);
@@ -1757,7 +1757,7 @@ public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMuta
 		/// <param name="selector">A transform function to apply to each element; the second parameter represents the zero-based index of the element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableArray<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableArray<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (selector);
@@ -1771,7 +1771,7 @@ public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMuta
 		/// <param name="keySelector">A function to extract a key from an element.</param>
 		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted according to a key.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
-		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (keySelector);
@@ -1785,7 +1785,7 @@ public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation
 		/// <param name="keySelector">A function to extract a key from an element.</param>
 		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted in descending order according to a key.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
-		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (keySelector);
@@ -1798,7 +1798,7 @@ public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this
 		/// <param name="count">The number of elements to skip before returning the remaining elements.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements after the skipped ones.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSMutableArray<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSMutableArray<TKey> source, int count) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Skip ((IEnumerable<TKey>) source, count);
@@ -1810,7 +1810,7 @@ public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSMutableArray<TKey>
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the elements starting at the first element that does not satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1823,7 +1823,7 @@ public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSMutableArray<
 		/// <param name="count">The number of elements to return.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the specified number of elements from the start of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSMutableArray<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSMutableArray<TKey> source, int count) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Take ((IEnumerable<TKey>) source, count);
@@ -1835,7 +1835,7 @@ public static IEnumerable<TKey> Take<TKey> (this Foundation.NSMutableArray<TKey>
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> as long as the condition is true.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1847,7 +1847,7 @@ public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSMutableArray<
 		/// <param name="source">The source collection.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains distinct elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Distinct ((IEnumerable<TKey>) source);
@@ -1858,7 +1858,7 @@ public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSMutableArray<T
 		/// <param name="source">The source collection.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements correspond to those of <paramref name="source"/> in reverse order.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Reverse ((IEnumerable<TKey>) source);
@@ -1870,7 +1870,7 @@ public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSMutableArray<TK
 		/// <param name="second">The sequence to concatenate to <paramref name="source"/>.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the concatenated elements of the two sequences.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="second"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSMutableArray<TKey> source, IEnumerable<TKey> second) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSMutableArray<TKey> source, IEnumerable<TKey> second) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (second);
@@ -1882,7 +1882,7 @@ public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSMutableArray<TKe
 		/// <param name="source">The source collection.</param>
 		/// <returns>A <see cref="List{T}"/> that contains elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static List<TKey> ToList<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static List<TKey> ToList<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ToList ((IEnumerable<TKey>) source);
@@ -1893,7 +1893,7 @@ public static List<TKey> ToList<TKey> (this Foundation.NSMutableArray<TKey> sour
 		/// <param name="source">The source collection.</param>
 		/// <returns>An array that contains elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey [] ToArray<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey [] ToArray<TKey> (this Foundation.NSMutableArray<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ToArray ((IEnumerable<TKey>) source);
@@ -1906,7 +1906,7 @@ public static TKey [] ToArray<TKey> (this Foundation.NSMutableArray<TKey> source
 		/// <returns>The final accumulator value.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey Aggregate<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, Foundation.INativeObject
+		public static TKey Aggregate<TKey> (this Foundation.NSMutableArray<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (func);
@@ -1921,7 +1921,7 @@ public static TKey Aggregate<TKey> (this Foundation.NSMutableArray<TKey> source,
 		/// <param name="func">An accumulator function to be invoked on each element.</param>
 		/// <returns>The final accumulator value.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
-		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSMutableArray<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, Foundation.INativeObject
+		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSMutableArray<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (func);
@@ -1935,7 +1935,7 @@ public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSMutabl
 		/// <returns>The first element in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey First<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey First<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.First ((IEnumerable<TKey>) source);
@@ -1948,7 +1948,7 @@ public static TKey First<TKey> (this Foundation.NSOrderedSet<TKey> source) where
 		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey First<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey First<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1960,7 +1960,7 @@ public static TKey First<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<
 		/// <param name="source">The source collection.</param>
 		/// <returns>The first element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
@@ -1972,7 +1972,7 @@ public static TKey First<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -1985,7 +1985,7 @@ public static TKey First<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<
 		/// <returns>The last element in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey Last<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey Last<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Last ((IEnumerable<TKey>) source);
@@ -1998,7 +1998,7 @@ public static TKey Last<TKey> (this Foundation.NSOrderedSet<TKey> source) where
 		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey Last<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey Last<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2010,7 +2010,7 @@ public static TKey Last<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<T
 		/// <param name="source">The source collection.</param>
 		/// <returns>The last element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? LastOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source);
@@ -2022,7 +2022,7 @@ public static TKey Last<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<T
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static TKey? LastOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2035,7 +2035,7 @@ public static TKey Last<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<T
 		/// <returns>The single element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty or contains more than one element.</exception>
-		public static TKey Single<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey Single<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Single ((IEnumerable<TKey>) source);
@@ -2048,7 +2048,7 @@ public static TKey Single<TKey> (this Foundation.NSOrderedSet<TKey> source) wher
 		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element or more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey Single<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey Single<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2061,7 +2061,7 @@ public static TKey Single<TKey> (this Foundation.NSOrderedSet<TKey> source, Func
 		/// <returns>The single element of <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> contains more than one element.</exception>
-		public static TKey? SingleOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source);
@@ -2074,7 +2074,7 @@ public static TKey Single<TKey> (this Foundation.NSOrderedSet<TKey> source, Func
 		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey? SingleOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2088,7 +2088,7 @@ public static TKey Single<TKey> (this Foundation.NSOrderedSet<TKey> source, Func
 		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="index"/> is less than 0 or greater than or equal to the number of elements in <paramref name="source"/>.</exception>
-		public static TKey ElementAt<TKey> (this Foundation.NSOrderedSet<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		public static TKey ElementAt<TKey> (this Foundation.NSOrderedSet<TKey> source, int index) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ElementAt ((IEnumerable<TKey>) source, index);
@@ -2100,7 +2100,7 @@ public static TKey ElementAt<TKey> (this Foundation.NSOrderedSet<TKey> source, i
 		/// <param name="index">The zero-based index of the element to retrieve.</param>
 		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>, or <see langword="null"/> if the index is out of range.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSOrderedSet<TKey> source, int index) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ElementAtOrDefault ((IEnumerable<TKey>) source, index);
@@ -2111,7 +2111,7 @@ public static TKey ElementAt<TKey> (this Foundation.NSOrderedSet<TKey> source, i
 		/// <param name="source">The source collection.</param>
 		/// <returns><see langword="true"/> if <paramref name="source"/> contains any elements; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static bool Any<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static bool Any<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Any ((IEnumerable<TKey>) source);
@@ -2123,7 +2123,7 @@ public static bool Any<TKey> (this Foundation.NSOrderedSet<TKey> source) where T
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns><see langword="true"/> if any element in <paramref name="source"/> passes the test in <paramref name="predicate"/>; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static bool Any<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static bool Any<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2136,7 +2136,7 @@ public static bool Any<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TK
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns><see langword="true"/> if every element in <paramref name="source"/> passes the test in <paramref name="predicate"/>, or if the collection is empty; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static bool All<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static bool All<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2148,7 +2148,7 @@ public static bool All<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TK
 		/// <param name="source">The source collection.</param>
 		/// <returns>The number of elements in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static int Count<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static int Count<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Count ((IEnumerable<TKey>) source);
@@ -2160,7 +2160,7 @@ public static int Count<TKey> (this Foundation.NSOrderedSet<TKey> source) where
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static int Count<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static int Count<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2172,7 +2172,7 @@ public static int Count<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<T
 		/// <param name="source">The source collection.</param>
 		/// <returns>The number of elements in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static long LongCount<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static long LongCount<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.LongCount ((IEnumerable<TKey>) source);
@@ -2184,7 +2184,7 @@ public static long LongCount<TKey> (this Foundation.NSOrderedSet<TKey> source) w
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static long LongCount<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static long LongCount<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2197,7 +2197,7 @@ public static long LongCount<TKey> (this Foundation.NSOrderedSet<TKey> source, F
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2210,7 +2210,7 @@ public static IEnumerable<TKey> Where<TKey> (this Foundation.NSOrderedSet<TKey>
 		/// <param name="predicate">A function to test each element; the second parameter represents the zero-based index of the element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2224,7 +2224,7 @@ public static IEnumerable<TKey> Where<TKey> (this Foundation.NSOrderedSet<TKey>
 		/// <param name="selector">A transform function to apply to each element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, TResult> selector) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, TResult> selector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (selector);
@@ -2238,7 +2238,7 @@ public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSOrde
 		/// <param name="selector">A transform function to apply to each element; the second parameter represents the zero-based index of the element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (selector);
@@ -2252,7 +2252,7 @@ public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSOrde
 		/// <param name="keySelector">A function to extract a key from an element.</param>
 		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted according to a key.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
-		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (keySelector);
@@ -2266,7 +2266,7 @@ public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation
 		/// <param name="keySelector">A function to extract a key from an element.</param>
 		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted in descending order according to a key.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
-		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (keySelector);
@@ -2279,7 +2279,7 @@ public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this
 		/// <param name="count">The number of elements to skip before returning the remaining elements.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements after the skipped ones.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSOrderedSet<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSOrderedSet<TKey> source, int count) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Skip ((IEnumerable<TKey>) source, count);
@@ -2291,7 +2291,7 @@ public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSOrderedSet<TKey> s
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the elements starting at the first element that does not satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2304,7 +2304,7 @@ public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSOrderedSet<TK
 		/// <param name="count">The number of elements to return.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the specified number of elements from the start of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSOrderedSet<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSOrderedSet<TKey> source, int count) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Take ((IEnumerable<TKey>) source, count);
@@ -2316,7 +2316,7 @@ public static IEnumerable<TKey> Take<TKey> (this Foundation.NSOrderedSet<TKey> s
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> as long as the condition is true.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2328,7 +2328,7 @@ public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSOrderedSet<TK
 		/// <param name="source">The source collection.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains distinct elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Distinct ((IEnumerable<TKey>) source);
@@ -2339,7 +2339,7 @@ public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSOrderedSet<TKe
 		/// <param name="source">The source collection.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements correspond to those of <paramref name="source"/> in reverse order.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Reverse ((IEnumerable<TKey>) source);
@@ -2351,7 +2351,7 @@ public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSOrderedSet<TKey
 		/// <param name="second">The sequence to concatenate to <paramref name="source"/>.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the concatenated elements of the two sequences.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="second"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSOrderedSet<TKey> source, IEnumerable<TKey> second) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSOrderedSet<TKey> source, IEnumerable<TKey> second) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (second);
@@ -2363,7 +2363,7 @@ public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSOrderedSet<TKey>
 		/// <param name="source">The source collection.</param>
 		/// <returns>A <see cref="List{T}"/> that contains elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static List<TKey> ToList<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static List<TKey> ToList<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ToList ((IEnumerable<TKey>) source);
@@ -2374,7 +2374,7 @@ public static List<TKey> ToList<TKey> (this Foundation.NSOrderedSet<TKey> source
 		/// <param name="source">The source collection.</param>
 		/// <returns>An array that contains elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey [] ToArray<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey [] ToArray<TKey> (this Foundation.NSOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ToArray ((IEnumerable<TKey>) source);
@@ -2387,7 +2387,7 @@ public static TKey [] ToArray<TKey> (this Foundation.NSOrderedSet<TKey> source)
 		/// <returns>The final accumulator value.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey Aggregate<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, Foundation.INativeObject
+		public static TKey Aggregate<TKey> (this Foundation.NSOrderedSet<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (func);
@@ -2402,7 +2402,7 @@ public static TKey Aggregate<TKey> (this Foundation.NSOrderedSet<TKey> source, F
 		/// <param name="func">An accumulator function to be invoked on each element.</param>
 		/// <returns>The final accumulator value.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
-		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSOrderedSet<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, Foundation.INativeObject
+		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSOrderedSet<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (func);
@@ -2416,7 +2416,7 @@ public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSOrdere
 		/// <returns>The first element in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey First<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey First<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.First ((IEnumerable<TKey>) source);
@@ -2429,7 +2429,7 @@ public static TKey First<TKey> (this Foundation.NSMutableOrderedSet<TKey> source
 		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey First<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey First<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2441,7 +2441,7 @@ public static TKey First<TKey> (this Foundation.NSMutableOrderedSet<TKey> source
 		/// <param name="source">The source collection.</param>
 		/// <returns>The first element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.FirstOrDefault ((IEnumerable<TKey>) source);
@@ -2453,7 +2453,7 @@ public static TKey First<TKey> (this Foundation.NSMutableOrderedSet<TKey> source
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The first element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? FirstOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2466,7 +2466,7 @@ public static TKey First<TKey> (this Foundation.NSMutableOrderedSet<TKey> source
 		/// <returns>The last element in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey Last<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey Last<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Last ((IEnumerable<TKey>) source);
@@ -2479,7 +2479,7 @@ public static TKey Last<TKey> (this Foundation.NSMutableOrderedSet<TKey> source)
 		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey Last<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey Last<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2491,7 +2491,7 @@ public static TKey Last<TKey> (this Foundation.NSMutableOrderedSet<TKey> source,
 		/// <param name="source">The source collection.</param>
 		/// <returns>The last element in <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.LastOrDefault ((IEnumerable<TKey>) source);
@@ -2503,7 +2503,7 @@ public static TKey Last<TKey> (this Foundation.NSMutableOrderedSet<TKey> source,
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The last element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? LastOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2516,7 +2516,7 @@ public static TKey Last<TKey> (this Foundation.NSMutableOrderedSet<TKey> source,
 		/// <returns>The single element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty or contains more than one element.</exception>
-		public static TKey Single<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey Single<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Single ((IEnumerable<TKey>) source);
@@ -2529,7 +2529,7 @@ public static TKey Single<TKey> (this Foundation.NSMutableOrderedSet<TKey> sourc
 		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when no element or more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey Single<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey Single<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2542,7 +2542,7 @@ public static TKey Single<TKey> (this Foundation.NSMutableOrderedSet<TKey> sourc
 		/// <returns>The single element of <paramref name="source"/>, or <see langword="null"/> if the collection is empty.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> contains more than one element.</exception>
-		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.SingleOrDefault ((IEnumerable<TKey>) source);
@@ -2555,7 +2555,7 @@ public static TKey Single<TKey> (this Foundation.NSMutableOrderedSet<TKey> sourc
 		/// <returns>The single element in <paramref name="source"/> that passes the test in <paramref name="predicate"/>, or <see langword="null"/> if no such element is found.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when more than one element satisfies the condition in <paramref name="predicate"/>.</exception>
-		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static TKey? SingleOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2569,7 +2569,7 @@ public static TKey Single<TKey> (this Foundation.NSMutableOrderedSet<TKey> sourc
 		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
 		/// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="index"/> is less than 0 or greater than or equal to the number of elements in <paramref name="source"/>.</exception>
-		public static TKey ElementAt<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		public static TKey ElementAt<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, int index) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ElementAt ((IEnumerable<TKey>) source, index);
@@ -2581,7 +2581,7 @@ public static TKey ElementAt<TKey> (this Foundation.NSMutableOrderedSet<TKey> so
 		/// <param name="index">The zero-based index of the element to retrieve.</param>
 		/// <returns>The element at position <paramref name="index"/> in <paramref name="source"/>, or <see langword="null"/> if the index is out of range.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, int index) where TKey : class, Foundation.INativeObject
+		public static TKey? ElementAtOrDefault<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, int index) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ElementAtOrDefault ((IEnumerable<TKey>) source, index);
@@ -2592,7 +2592,7 @@ public static TKey ElementAt<TKey> (this Foundation.NSMutableOrderedSet<TKey> so
 		/// <param name="source">The source collection.</param>
 		/// <returns><see langword="true"/> if <paramref name="source"/> contains any elements; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static bool Any<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static bool Any<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Any ((IEnumerable<TKey>) source);
@@ -2604,7 +2604,7 @@ public static bool Any<TKey> (this Foundation.NSMutableOrderedSet<TKey> source)
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns><see langword="true"/> if any element in <paramref name="source"/> passes the test in <paramref name="predicate"/>; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static bool Any<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static bool Any<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2617,7 +2617,7 @@ public static bool Any<TKey> (this Foundation.NSMutableOrderedSet<TKey> source,
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns><see langword="true"/> if every element in <paramref name="source"/> passes the test in <paramref name="predicate"/>, or if the collection is empty; otherwise <see langword="false"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static bool All<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static bool All<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2629,7 +2629,7 @@ public static bool All<TKey> (this Foundation.NSMutableOrderedSet<TKey> source,
 		/// <param name="source">The source collection.</param>
 		/// <returns>The number of elements in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static int Count<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static int Count<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Count ((IEnumerable<TKey>) source);
@@ -2641,7 +2641,7 @@ public static int Count<TKey> (this Foundation.NSMutableOrderedSet<TKey> source)
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static int Count<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static int Count<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2653,7 +2653,7 @@ public static int Count<TKey> (this Foundation.NSMutableOrderedSet<TKey> source,
 		/// <param name="source">The source collection.</param>
 		/// <returns>The number of elements in <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static long LongCount<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static long LongCount<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.LongCount ((IEnumerable<TKey>) source);
@@ -2665,7 +2665,7 @@ public static long LongCount<TKey> (this Foundation.NSMutableOrderedSet<TKey> so
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>The number of elements in <paramref name="source"/> that pass the test in <paramref name="predicate"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static long LongCount<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static long LongCount<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2678,7 +2678,7 @@ public static long LongCount<TKey> (this Foundation.NSMutableOrderedSet<TKey> so
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2691,7 +2691,7 @@ public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableOrderedSet
 		/// <param name="predicate">A function to test each element; the second parameter represents the zero-based index of the element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> that satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, int, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2705,7 +2705,7 @@ public static IEnumerable<TKey> Where<TKey> (this Foundation.NSMutableOrderedSet
 		/// <param name="selector">A transform function to apply to each element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, TResult> selector) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, TResult> selector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (selector);
@@ -2719,7 +2719,7 @@ public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMuta
 		/// <param name="selector">A transform function to apply to each element; the second parameter represents the zero-based index of the element.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements are the result of invoking the transform function on each element of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="selector"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, int, TResult> selector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (selector);
@@ -2733,7 +2733,7 @@ public static IEnumerable<TResult> Select<TKey, TResult> (this Foundation.NSMuta
 		/// <param name="keySelector">A function to extract a key from an element.</param>
 		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted according to a key.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
-		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (keySelector);
@@ -2747,7 +2747,7 @@ public static IOrderedEnumerable<TKey> OrderBy<TKey, TOrderKey> (this Foundation
 		/// <param name="keySelector">A function to extract a key from an element.</param>
 		/// <returns>An <see cref="IOrderedEnumerable{T}"/> whose elements are sorted in descending order according to a key.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="keySelector"/> is <see langword="null"/>.</exception>
-		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, Foundation.INativeObject
+		public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, TOrderKey> keySelector) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (keySelector);
@@ -2760,7 +2760,7 @@ public static IOrderedEnumerable<TKey> OrderByDescending<TKey, TOrderKey> (this
 		/// <param name="count">The number of elements to skip before returning the remaining elements.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements after the skipped ones.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, int count) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Skip ((IEnumerable<TKey>) source, count);
@@ -2772,7 +2772,7 @@ public static IEnumerable<TKey> Skip<TKey> (this Foundation.NSMutableOrderedSet<
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the elements starting at the first element that does not satisfy the condition.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2785,7 +2785,7 @@ public static IEnumerable<TKey> SkipWhile<TKey> (this Foundation.NSMutableOrdere
 		/// <param name="count">The number of elements to return.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the specified number of elements from the start of <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, int count) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Take<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, int count) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Take ((IEnumerable<TKey>) source, count);
@@ -2797,7 +2797,7 @@ public static IEnumerable<TKey> Take<TKey> (this Foundation.NSMutableOrderedSet<
 		/// <param name="predicate">A function to test each element for a condition.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains elements from <paramref name="source"/> as long as the condition is true.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="predicate"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, bool> predicate) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (predicate);
@@ -2809,7 +2809,7 @@ public static IEnumerable<TKey> TakeWhile<TKey> (this Foundation.NSMutableOrdere
 		/// <param name="source">The source collection.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains distinct elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Distinct ((IEnumerable<TKey>) source);
@@ -2820,7 +2820,7 @@ public static IEnumerable<TKey> Distinct<TKey> (this Foundation.NSMutableOrdered
 		/// <param name="source">The source collection.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> whose elements correspond to those of <paramref name="source"/> in reverse order.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.Reverse ((IEnumerable<TKey>) source);
@@ -2832,7 +2832,7 @@ public static IEnumerable<TKey> Reverse<TKey> (this Foundation.NSMutableOrderedS
 		/// <param name="second">The sequence to concatenate to <paramref name="source"/>.</param>
 		/// <returns>An <see cref="IEnumerable{T}"/> that contains the concatenated elements of the two sequences.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="second"/> is <see langword="null"/>.</exception>
-		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, IEnumerable<TKey> second) where TKey : class, Foundation.INativeObject
+		public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, IEnumerable<TKey> second) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (second);
@@ -2844,7 +2844,7 @@ public static IEnumerable<TKey> Concat<TKey> (this Foundation.NSMutableOrderedSe
 		/// <param name="source">The source collection.</param>
 		/// <returns>A <see cref="List{T}"/> that contains elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static List<TKey> ToList<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static List<TKey> ToList<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ToList ((IEnumerable<TKey>) source);
@@ -2855,7 +2855,7 @@ public static List<TKey> ToList<TKey> (this Foundation.NSMutableOrderedSet<TKey>
 		/// <param name="source">The source collection.</param>
 		/// <returns>An array that contains elements from <paramref name="source"/>.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> is <see langword="null"/>.</exception>
-		public static TKey [] ToArray<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, Foundation.INativeObject
+		public static TKey [] ToArray<TKey> (this Foundation.NSMutableOrderedSet<TKey> source) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			return Enumerable.ToArray ((IEnumerable<TKey>) source);
@@ -2868,7 +2868,7 @@ public static TKey [] ToArray<TKey> (this Foundation.NSMutableOrderedSet<TKey> s
 		/// <returns>The final accumulator value.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
 		/// <exception cref="InvalidOperationException">Thrown when <paramref name="source"/> is empty.</exception>
-		public static TKey Aggregate<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, Foundation.INativeObject
+		public static TKey Aggregate<TKey> (this Foundation.NSMutableOrderedSet<TKey> source, Func<TKey, TKey, TKey> func) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (func);
@@ -2883,7 +2883,7 @@ public static TKey Aggregate<TKey> (this Foundation.NSMutableOrderedSet<TKey> so
 		/// <param name="func">An accumulator function to be invoked on each element.</param>
 		/// <returns>The final accumulator value.</returns>
 		/// <exception cref="ArgumentNullException">Thrown when <paramref name="source"/> or <paramref name="func"/> is <see langword="null"/>.</exception>
-		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSMutableOrderedSet<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, Foundation.INativeObject
+		public static TAccumulate Aggregate<TKey, TAccumulate> (this Foundation.NSMutableOrderedSet<TKey> source, TAccumulate seed, Func<TAccumulate, TKey, TAccumulate> func) where TKey : class, ObjCRuntime.INativeObject
 		{
 			ArgumentNullException.ThrowIfNull (source);
 			ArgumentNullException.ThrowIfNull (func);

From 56709b2e806746948448b35df01ab10a3e65d98b Mon Sep 17 00:00:00 2001
From: GitHub Actions Autoformatter <github-actions-autoformatter@xamarin.com>
Date: Wed, 27 May 2026 15:59:35 +0000
Subject: [PATCH 6/6] Auto-format source code

---
 .../Foundation/NSCollectionLinqTest.cs        | 3022 ++++++++---------
 1 file changed, 1511 insertions(+), 1511 deletions(-)

diff --git a/tests/monotouch-test/Foundation/NSCollectionLinqTest.cs b/tests/monotouch-test/Foundation/NSCollectionLinqTest.cs
index 23ae501d5075..03ab33120969 100644
--- a/tests/monotouch-test/Foundation/NSCollectionLinqTest.cs
+++ b/tests/monotouch-test/Foundation/NSCollectionLinqTest.cs
@@ -7,1515 +7,1515 @@
 
 namespace MonoTouchFixtures.Foundation {
 
-[TestFixture]
-[Preserve (AllMembers = true)]
-public class NSCollectionLinqTest {
-
-// ----- helpers -----
-
-static NSString S (string s) => (NSString) s;
-
-static NSSet<NSString> MakeSet (params string [] items)
-{
-return new NSSet<NSString> (items.Select (S).ToArray ());
-}
-
-static NSMutableSet<NSString> MakeMutableSet (params string [] items)
-{
-return new NSMutableSet<NSString> (items.Select (S).ToArray ());
-}
-
-static NSArray<NSString> MakeArray (params string [] items)
-{
-return NSArray<NSString>.FromNSObjects (items.Select (S).ToArray ());
-}
-
-static NSMutableArray<NSString> MakeMutableArray (params string [] items)
-{
-var arr = new NSMutableArray<NSString> ();
-foreach (var s in items)
-arr.Add (S (s));
-return arr;
-}
-
-static NSOrderedSet<NSString> MakeOrderedSet (params string [] items)
-{
-return new NSOrderedSet<NSString> (items.Select (S).ToArray ());
-}
-
-static NSMutableOrderedSet<NSString> MakeMutableOrderedSet (params string [] items)
-{
-var set = new NSMutableOrderedSet<NSString> ();
-foreach (var s in items)
-set.Add (S (s));
-return set;
-}
-
-// ===== NSSet<T> =====
-
-[Test]
-public void NSSet_First ()
-{
-using var set = MakeSet ("a");
-var first = set.First ();
-Assert.That (first.ToString (), Is.EqualTo ("a"), "First");
-}
-
-[Test]
-public void NSSet_First_Predicate ()
-{
-using var set = MakeSet ("a", "b", "c");
-var found = set.First (s => s.ToString () == "b");
-Assert.That (found.ToString (), Is.EqualTo ("b"), "First predicate");
-}
-
-[Test]
-public void NSSet_First_Empty_Throws ()
-{
-using var set = MakeSet ();
-Assert.Throws<InvalidOperationException> (() => set.First ());
-}
-
-[Test]
-public void NSSet_FirstOrDefault_Empty ()
-{
-using var set = MakeSet ();
-Assert.That (set.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
-}
-
-[Test]
-public void NSSet_FirstOrDefault ()
-{
-using var set = MakeSet ("x");
-Assert.That (set.FirstOrDefault (), Is.Not.Null, "FirstOrDefault");
-}
-
-[Test]
-public void NSSet_FirstOrDefault_Predicate_NoMatch ()
-{
-using var set = MakeSet ("a", "b");
-Assert.That (set.FirstOrDefault (s => s.ToString () == "z"), Is.Null, "no match");
-}
-
-[Test]
-public void NSSet_Last ()
-{
-using var set = MakeSet ("a");
-var last = set.Last ();
-Assert.That (last.ToString (), Is.EqualTo ("a"), "Last");
-}
-
-[Test]
-public void NSSet_Last_Predicate ()
-{
-using var set = MakeSet ("a", "b", "c");
-var found = set.Last (s => s.ToString () != "c");
-Assert.That (found, Is.Not.Null, "Last predicate not null");
-}
-
-[Test]
-public void NSSet_Last_Empty_Throws ()
-{
-using var set = MakeSet ();
-Assert.Throws<InvalidOperationException> (() => set.Last ());
-}
-
-[Test]
-public void NSSet_LastOrDefault_Empty ()
-{
-using var set = MakeSet ();
-Assert.That (set.LastOrDefault (), Is.Null, "LastOrDefault empty");
-}
-
-[Test]
-public void NSSet_LastOrDefault_Predicate_NoMatch ()
-{
-using var set = MakeSet ("a");
-Assert.That (set.LastOrDefault (s => s.ToString () == "z"), Is.Null, "LastOrDefault no match");
-}
-
-[Test]
-public void NSSet_Single ()
-{
-using var set = MakeSet ("only");
-Assert.That (set.Single ().ToString (), Is.EqualTo ("only"), "Single");
-}
-
-[Test]
-public void NSSet_Single_Throws_OnMultiple ()
-{
-using var set = MakeSet ("a", "b");
-Assert.Throws<InvalidOperationException> (() => set.Single ());
-}
-
-[Test]
-public void NSSet_SingleOrDefault_Empty ()
-{
-using var set = MakeSet ();
-Assert.That (set.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
-}
-
-[Test]
-public void NSSet_SingleOrDefault_Predicate ()
-{
-using var set = MakeSet ("a", "b");
-Assert.That (set.SingleOrDefault (s => s.ToString () == "a")?.ToString (), Is.EqualTo ("a"), "SingleOrDefault predicate");
-}
-
-[Test]
-public void NSSet_Any_Empty ()
-{
-using var set = MakeSet ();
-Assert.That (set.Any (), Is.False, "Any empty");
-}
-
-[Test]
-public void NSSet_Any_NonEmpty ()
-{
-using var set = MakeSet ("a");
-Assert.That (set.Any (), Is.True, "Any non-empty");
-}
-
-[Test]
-public void NSSet_Any_Predicate ()
-{
-using var set = MakeSet ("a", "b");
-Assert.That (set.Any (s => s.ToString () == "b"), Is.True, "Any predicate true");
-Assert.That (set.Any (s => s.ToString () == "z"), Is.False, "Any predicate false");
-}
-
-[Test]
-public void NSSet_All ()
-{
-using var set = MakeSet ("ab", "abc");
-Assert.That (set.All (s => s.Length > 1), Is.True, "All true");
-Assert.That (set.All (s => s.Length > 2), Is.False, "All false");
-}
-
-[Test]
-public void NSSet_Count ()
-{
-using var set = MakeSet ("a", "b", "c");
-Assert.That (set.Count (), Is.EqualTo (3), "Count");
-Assert.That (set.Count (s => s.ToString () == "a"), Is.EqualTo (1), "Count predicate");
-}
-
-[Test]
-public void NSSet_LongCount ()
-{
-using var set = MakeSet ("a", "b");
-Assert.That (set.LongCount (), Is.EqualTo (2L), "LongCount");
-Assert.That (set.LongCount (s => s.ToString () == "a"), Is.EqualTo (1L), "LongCount predicate");
-}
-
-[Test]
-public void NSSet_Where ()
-{
-using var set = MakeSet ("a", "bb", "ccc");
-var result = set.Where (s => s.Length > 1).ToList ();
-Assert.That (result.Count, Is.EqualTo (2), "Where count");
-}
-
-[Test]
-public void NSSet_Where_Index ()
-{
-using var arr = MakeOrderedSet ("a", "b", "c");
-var result = arr.Where ((s, i) => i % 2 == 0).ToList ();
-Assert.That (result.Count, Is.EqualTo (2), "Where index count");
-}
-
-[Test]
-public void NSSet_Select ()
-{
-using var set = MakeSet ("hello");
-var lengths = set.Select (s => s.Length).ToList ();
-Assert.That (lengths, Contains.Item (5), "Select length");
-}
-
-[Test]
-public void NSSet_Select_Index ()
-{
-using var arr = MakeOrderedSet ("a", "b", "c");
-var indexed = arr.Select ((s, i) => $"{i}:{s}").ToList ();
-Assert.That (indexed [0], Is.EqualTo ("0:a"), "Select index 0");
-Assert.That (indexed [1], Is.EqualTo ("1:b"), "Select index 1");
-}
-
-[Test]
-public void NSSet_OrderBy ()
-{
-using var set = MakeSet ("banana", "apple", "cherry");
-var sorted = set.OrderBy (s => s.ToString ()).ToList ();
-Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
-Assert.That (sorted [2].ToString (), Is.EqualTo ("cherry"), "OrderBy last");
-}
-
-[Test]
-public void NSSet_OrderByDescending ()
-{
-using var set = MakeSet ("banana", "apple", "cherry");
-var sorted = set.OrderByDescending (s => s.ToString ()).ToList ();
-Assert.That (sorted [0].ToString (), Is.EqualTo ("cherry"), "OrderByDesc first");
-}
-
-[Test]
-public void NSSet_Distinct ()
-{
-using var set = MakeSet ("a", "b", "b");
-// NSSet already ensures uniqueness, but verify Distinct works
-var distinct = set.Distinct ().ToList ();
-Assert.That (distinct.Count, Is.EqualTo (2), "Distinct count");
-}
-
-[Test]
-public void NSSet_Reverse ()
-{
-using var arr = MakeOrderedSet ("a", "b", "c");
-var reversed = arr.Reverse ().ToList ();
-Assert.That (reversed [0].ToString (), Is.EqualTo ("c"), "Reverse first");
-Assert.That (reversed [2].ToString (), Is.EqualTo ("a"), "Reverse last");
-}
-
-[Test]
-public void NSSet_Concat ()
-{
-using var set = MakeSet ("a", "b");
-var extra = new [] { S ("c"), S ("d") };
-var all = set.Concat (extra).ToList ();
-Assert.That (all.Count, Is.EqualTo (4), "Concat count");
-}
-
-[Test]
-public void NSSet_Skip_Take ()
-{
-using var arr = MakeOrderedSet ("a", "b", "c", "d");
-var sliced = arr.Skip (1).Take (2).ToList ();
-Assert.That (sliced.Count, Is.EqualTo (2), "Skip/Take count");
-Assert.That (sliced [0].ToString (), Is.EqualTo ("b"), "Skip/Take first");
-}
-
-[Test]
-public void NSSet_SkipWhile_TakeWhile ()
-{
-using var arr = MakeOrderedSet ("a", "b", "c");
-var skipped = arr.SkipWhile (s => s.ToString () == "a").ToList ();
-Assert.That (skipped.Count, Is.EqualTo (2), "SkipWhile count");
-
-var taken = arr.TakeWhile (s => s.ToString () != "c").ToList ();
-Assert.That (taken.Count, Is.EqualTo (2), "TakeWhile count");
-}
-
-[Test]
-public void NSSet_ElementAt ()
-{
-using var arr = MakeOrderedSet ("a", "b", "c");
-Assert.That (arr.ElementAt (1).ToString (), Is.EqualTo ("b"), "ElementAt");
-}
-
-[Test]
-public void NSSet_ElementAtOrDefault ()
-{
-using var arr = MakeOrderedSet ("a", "b");
-Assert.That (arr.ElementAtOrDefault (0), Is.Not.Null, "ElementAtOrDefault in range");
-Assert.That (arr.ElementAtOrDefault (99), Is.Null, "ElementAtOrDefault out of range");
-}
-
-[Test]
-public void NSSet_ToList ()
-{
-using var set = MakeSet ("a", "b");
-var list = set.ToList ();
-Assert.That (list, Is.TypeOf<List<NSString>> (), "ToList type");
-Assert.That (list.Count, Is.EqualTo (2), "ToList count");
-}
-
-[Test]
-public void NSSet_ToArray ()
-{
-using var set = MakeSet ("a", "b");
-var arr = set.ToArray ();
-Assert.That (arr, Is.TypeOf<NSString []> (), "ToArray type");
-Assert.That (arr.Length, Is.EqualTo (2), "ToArray length");
-}
-
-[Test]
-public void NSSet_Aggregate ()
-{
-using var arr = MakeOrderedSet ("a", "b", "c");
-var result = arr.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
-Assert.That (result.ToString (), Is.EqualTo ("abc"), "Aggregate");
-}
-
-[Test]
-public void NSSet_Aggregate_Seed ()
-{
-using var arr = MakeOrderedSet ("a", "b", "c");
-var result = arr.Aggregate ("", (acc, s) => acc + s.ToString ());
-Assert.That (result, Is.EqualTo ("abc"), "Aggregate seed");
-}
-
-// ===== NSMutableSet<T> =====
-
-[Test]
-public void NSMutableSet_First ()
-{
-using var set = MakeMutableSet ("a");
-Assert.That (set.First ().ToString (), Is.EqualTo ("a"), "First");
-}
-
-[Test]
-public void NSMutableSet_FirstOrDefault_Empty ()
-{
-using var set = MakeMutableSet ();
-Assert.That (set.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
-}
-
-[Test]
-public void NSMutableSet_Last ()
-{
-using var set = MakeMutableSet ("a");
-Assert.That (set.Last ().ToString (), Is.EqualTo ("a"), "Last");
-}
-
-[Test]
-public void NSMutableSet_LastOrDefault_Empty ()
-{
-using var set = MakeMutableSet ();
-Assert.That (set.LastOrDefault (), Is.Null, "LastOrDefault empty");
-}
-
-[Test]
-public void NSMutableSet_Single ()
-{
-using var set = MakeMutableSet ("only");
-Assert.That (set.Single ().ToString (), Is.EqualTo ("only"), "Single");
-}
-
-[Test]
-public void NSMutableSet_SingleOrDefault_Empty ()
-{
-using var set = MakeMutableSet ();
-Assert.That (set.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
-}
-
-[Test]
-public void NSMutableSet_Any ()
-{
-using var set = MakeMutableSet ();
-Assert.That (set.Any (), Is.False, "Any empty");
-using var set2 = MakeMutableSet ("a");
-Assert.That (set2.Any (), Is.True, "Any non-empty");
-}
-
-[Test]
-public void NSMutableSet_All ()
-{
-using var set = MakeMutableSet ("ab", "abc");
-Assert.That (set.All (s => s.Length > 1), Is.True, "All true");
-}
-
-[Test]
-public void NSMutableSet_Count ()
-{
-using var set = MakeMutableSet ("a", "b", "c");
-Assert.That (set.Count (), Is.EqualTo (3), "Count");
-}
-
-[Test]
-public void NSMutableSet_LongCount ()
-{
-using var set = MakeMutableSet ("a", "b");
-Assert.That (set.LongCount (), Is.EqualTo (2L), "LongCount");
-}
-
-[Test]
-public void NSMutableSet_Where ()
-{
-using var set = MakeMutableSet ("a", "bb", "ccc");
-var result = set.Where (s => s.Length > 1).ToList ();
-Assert.That (result.Count, Is.EqualTo (2), "Where count");
-}
-
-[Test]
-public void NSMutableSet_Select ()
-{
-using var set = MakeMutableSet ("hello");
-var lengths = set.Select (s => s.Length).ToList ();
-Assert.That (lengths, Contains.Item (5), "Select length");
-}
-
-[Test]
-public void NSMutableSet_OrderBy ()
-{
-using var set = MakeMutableSet ("banana", "apple", "cherry");
-var sorted = set.OrderBy (s => s.ToString ()).ToList ();
-Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
-}
-
-[Test]
-public void NSMutableSet_Skip_Take ()
-{
-using var arr = MakeOrderedSet ("a", "b", "c", "d");
-var sliced = arr.Skip (1).Take (2).ToList ();
-Assert.That (sliced.Count, Is.EqualTo (2), "Skip/Take count");
-}
-
-[Test]
-public void NSMutableSet_ToList ()
-{
-using var set = MakeMutableSet ("a", "b");
-var list = set.ToList ();
-Assert.That (list.Count, Is.EqualTo (2), "ToList count");
-}
-
-[Test]
-public void NSMutableSet_ToArray ()
-{
-using var set = MakeMutableSet ("a", "b");
-var arr = set.ToArray ();
-Assert.That (arr.Length, Is.EqualTo (2), "ToArray length");
-}
-
-[Test]
-public void NSMutableSet_Aggregate ()
-{
-using var set = MakeMutableSet ("a");
-var result = set.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
-Assert.That (result.ToString (), Is.EqualTo ("a"), "Aggregate");
-}
-
-// ===== NSArray<T> =====
-
-[Test]
-public void NSArray_First ()
-{
-using var arr = MakeArray ("a", "b", "c");
-Assert.That (arr.First ().ToString (), Is.EqualTo ("a"), "First");
-}
-
-[Test]
-public void NSArray_First_Predicate ()
-{
-using var arr = MakeArray ("a", "b", "c");
-Assert.That (arr.First (s => s.ToString () == "b").ToString (), Is.EqualTo ("b"), "First predicate");
-}
-
-[Test]
-public void NSArray_First_Empty_Throws ()
-{
-using var arr = MakeArray ();
-Assert.Throws<InvalidOperationException> (() => arr.First ());
-}
-
-[Test]
-public void NSArray_FirstOrDefault_Empty ()
-{
-using var arr = MakeArray ();
-Assert.That (arr.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
-}
-
-[Test]
-public void NSArray_FirstOrDefault ()
-{
-using var arr = MakeArray ("x", "y");
-Assert.That (arr.FirstOrDefault ()?.ToString (), Is.EqualTo ("x"), "FirstOrDefault");
-}
-
-[Test]
-public void NSArray_FirstOrDefault_Predicate ()
-{
-using var arr = MakeArray ("a", "b", "c");
-Assert.That (arr.FirstOrDefault (s => s.ToString () == "b")?.ToString (), Is.EqualTo ("b"), "FirstOrDefault predicate match");
-Assert.That (arr.FirstOrDefault (s => s.ToString () == "z"), Is.Null, "FirstOrDefault predicate no match");
-}
-
-[Test]
-public void NSArray_Last ()
-{
-using var arr = MakeArray ("a", "b", "c");
-Assert.That (arr.Last ().ToString (), Is.EqualTo ("c"), "Last");
-}
-
-[Test]
-public void NSArray_Last_Predicate ()
-{
-using var arr = MakeArray ("a", "b", "c");
-Assert.That (arr.Last (s => s.ToString () != "c").ToString (), Is.EqualTo ("b"), "Last predicate");
-}
-
-[Test]
-public void NSArray_Last_Empty_Throws ()
-{
-using var arr = MakeArray ();
-Assert.Throws<InvalidOperationException> (() => arr.Last ());
-}
-
-[Test]
-public void NSArray_LastOrDefault_Empty ()
-{
-using var arr = MakeArray ();
-Assert.That (arr.LastOrDefault (), Is.Null, "LastOrDefault empty");
-}
-
-[Test]
-public void NSArray_LastOrDefault_Predicate_NoMatch ()
-{
-using var arr = MakeArray ("a", "b");
-Assert.That (arr.LastOrDefault (s => s.ToString () == "z"), Is.Null, "LastOrDefault no match");
-}
-
-[Test]
-public void NSArray_Single ()
-{
-using var arr = MakeArray ("only");
-Assert.That (arr.Single ().ToString (), Is.EqualTo ("only"), "Single");
-}
-
-[Test]
-public void NSArray_Single_Throws_OnEmpty ()
-{
-using var arr = MakeArray ();
-Assert.Throws<InvalidOperationException> (() => arr.Single ());
-}
-
-[Test]
-public void NSArray_Single_Throws_OnMultiple ()
-{
-using var arr = MakeArray ("a", "b");
-Assert.Throws<InvalidOperationException> (() => arr.Single ());
-}
-
-[Test]
-public void NSArray_SingleOrDefault_Empty ()
-{
-using var arr = MakeArray ();
-Assert.That (arr.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
-}
-
-[Test]
-public void NSArray_SingleOrDefault_Predicate ()
-{
-using var arr = MakeArray ("a", "b");
-Assert.That (arr.SingleOrDefault (s => s.ToString () == "a")?.ToString (), Is.EqualTo ("a"), "SingleOrDefault predicate match");
-Assert.That (arr.SingleOrDefault (s => s.ToString () == "z"), Is.Null, "SingleOrDefault predicate no match");
-}
-
-[Test]
-public void NSArray_ElementAt ()
-{
-using var arr = MakeArray ("a", "b", "c");
-Assert.That (arr.ElementAt (0).ToString (), Is.EqualTo ("a"), "ElementAt 0");
-Assert.That (arr.ElementAt (2).ToString (), Is.EqualTo ("c"), "ElementAt 2");
-}
-
-[Test]
-public void NSArray_ElementAt_OutOfRange_Throws ()
-{
-using var arr = MakeArray ("a");
-Assert.Throws<ArgumentOutOfRangeException> (() => arr.ElementAt (5));
-}
-
-[Test]
-public void NSArray_ElementAtOrDefault ()
-{
-using var arr = MakeArray ("a", "b");
-Assert.That (arr.ElementAtOrDefault (1)?.ToString (), Is.EqualTo ("b"), "ElementAtOrDefault in range");
-Assert.That (arr.ElementAtOrDefault (99), Is.Null, "ElementAtOrDefault out of range");
-}
-
-[Test]
-public void NSArray_Any ()
-{
-using var empty = MakeArray ();
-Assert.That (empty.Any (), Is.False, "Any empty");
-using var arr = MakeArray ("a");
-Assert.That (arr.Any (), Is.True, "Any non-empty");
-Assert.That (arr.Any (s => s.ToString () == "a"), Is.True, "Any predicate true");
-Assert.That (arr.Any (s => s.ToString () == "z"), Is.False, "Any predicate false");
-}
-
-[Test]
-public void NSArray_All ()
-{
-using var arr = MakeArray ("ab", "abc");
-Assert.That (arr.All (s => s.Length > 1), Is.True, "All true");
-Assert.That (arr.All (s => s.Length > 2), Is.False, "All false");
-}
-
-[Test]
-public void NSArray_Count ()
-{
-using var arr = MakeArray ("a", "b", "c");
-Assert.That (arr.Count (), Is.EqualTo (3), "Count");
-Assert.That (arr.Count (s => s.ToString () == "a"), Is.EqualTo (1), "Count predicate");
-}
-
-[Test]
-public void NSArray_LongCount ()
-{
-using var arr = MakeArray ("a", "b");
-Assert.That (arr.LongCount (), Is.EqualTo (2L), "LongCount");
-Assert.That (arr.LongCount (s => s.ToString () == "a"), Is.EqualTo (1L), "LongCount predicate");
-}
-
-[Test]
-public void NSArray_Where ()
-{
-using var arr = MakeArray ("a", "bb", "ccc");
-var result = arr.Where (s => s.Length > 1).ToList ();
-Assert.That (result.Count, Is.EqualTo (2), "Where count");
-}
-
-[Test]
-public void NSArray_Where_Index ()
-{
-using var arr = MakeArray ("a", "b", "c");
-var result = arr.Where ((s, i) => i % 2 == 0).ToList ();
-Assert.That (result.Count, Is.EqualTo (2), "Where index count");
-Assert.That (result [0].ToString (), Is.EqualTo ("a"), "Where index [0]");
-Assert.That (result [1].ToString (), Is.EqualTo ("c"), "Where index [1]");
-}
-
-[Test]
-public void NSArray_Select ()
-{
-using var arr = MakeArray ("hello", "world");
-var lengths = arr.Select (s => s.Length).ToList ();
-Assert.That (lengths [0], Is.EqualTo (5), "Select length [0]");
-Assert.That (lengths [1], Is.EqualTo (5), "Select length [1]");
-}
-
-[Test]
-public void NSArray_Select_Index ()
-{
-using var arr = MakeArray ("a", "b", "c");
-var indexed = arr.Select ((s, i) => $"{i}:{s}").ToList ();
-Assert.That (indexed [0], Is.EqualTo ("0:a"), "Select index 0");
-Assert.That (indexed [2], Is.EqualTo ("2:c"), "Select index 2");
-}
-
-[Test]
-public void NSArray_OrderBy ()
-{
-using var arr = MakeArray ("banana", "apple", "cherry");
-var sorted = arr.OrderBy (s => s.ToString ()).ToList ();
-Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
-Assert.That (sorted [1].ToString (), Is.EqualTo ("banana"), "OrderBy second");
-Assert.That (sorted [2].ToString (), Is.EqualTo ("cherry"), "OrderBy third");
-}
-
-[Test]
-public void NSArray_OrderByDescending ()
-{
-using var arr = MakeArray ("banana", "apple", "cherry");
-var sorted = arr.OrderByDescending (s => s.ToString ()).ToList ();
-Assert.That (sorted [0].ToString (), Is.EqualTo ("cherry"), "OrderByDesc first");
-Assert.That (sorted [2].ToString (), Is.EqualTo ("apple"), "OrderByDesc last");
-}
-
-[Test]
-public void NSArray_Skip ()
-{
-using var arr = MakeArray ("a", "b", "c", "d");
-var skipped = arr.Skip (2).ToList ();
-Assert.That (skipped.Count, Is.EqualTo (2), "Skip count");
-Assert.That (skipped [0].ToString (), Is.EqualTo ("c"), "Skip [0]");
-}
-
-[Test]
-public void NSArray_SkipWhile ()
-{
-using var arr = MakeArray ("a", "b", "c");
-var result = arr.SkipWhile (s => s.ToString () != "b").ToList ();
-Assert.That (result.Count, Is.EqualTo (2), "SkipWhile count");
-Assert.That (result [0].ToString (), Is.EqualTo ("b"), "SkipWhile first");
-}
-
-[Test]
-public void NSArray_Take ()
-{
-using var arr = MakeArray ("a", "b", "c");
-var taken = arr.Take (2).ToList ();
-Assert.That (taken.Count, Is.EqualTo (2), "Take count");
-Assert.That (taken [1].ToString (), Is.EqualTo ("b"), "Take [1]");
-}
-
-[Test]
-public void NSArray_TakeWhile ()
-{
-using var arr = MakeArray ("a", "b", "c");
-var taken = arr.TakeWhile (s => s.ToString () != "c").ToList ();
-Assert.That (taken.Count, Is.EqualTo (2), "TakeWhile count");
-}
-
-[Test]
-public void NSArray_Distinct ()
-{
-using var arr = MakeArray ("a", "a", "b");
-var distinct = arr.Distinct ().ToList ();
-Assert.That (distinct.Count, Is.EqualTo (2), "Distinct count");
-}
-
-[Test]
-public void NSArray_Reverse ()
-{
-using var arr = MakeArray ("a", "b", "c");
-var reversed = arr.Reverse ().ToList ();
-Assert.That (reversed [0].ToString (), Is.EqualTo ("c"), "Reverse [0]");
-Assert.That (reversed [2].ToString (), Is.EqualTo ("a"), "Reverse [2]");
-}
-
-[Test]
-public void NSArray_Concat ()
-{
-using var arr = MakeArray ("a", "b");
-var extra = new [] { S ("c") };
-var all = arr.Concat (extra).ToList ();
-Assert.That (all.Count, Is.EqualTo (3), "Concat count");
-Assert.That (all [2].ToString (), Is.EqualTo ("c"), "Concat last");
-}
-
-[Test]
-public void NSArray_ToList ()
-{
-using var arr = MakeArray ("a", "b", "c");
-var list = arr.ToList ();
-Assert.That (list, Is.TypeOf<List<NSString>> (), "ToList type");
-Assert.That (list.Count, Is.EqualTo (3), "ToList count");
-}
-
-[Test]
-public void NSArray_ToArray ()
-{
-using var arr = MakeArray ("a", "b");
-var result = arr.ToArray ();
-Assert.That (result, Is.TypeOf<NSString []> (), "ToArray type");
-Assert.That (result.Length, Is.EqualTo (2), "ToArray length");
-}
-
-[Test]
-public void NSArray_Aggregate ()
-{
-using var arr = MakeArray ("a", "b", "c");
-var result = arr.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
-Assert.That (result.ToString (), Is.EqualTo ("abc"), "Aggregate");
-}
-
-[Test]
-public void NSArray_Aggregate_Seed ()
-{
-using var arr = MakeArray ("a", "b", "c");
-var result = arr.Aggregate ("", (acc, s) => acc + s.ToString ());
-Assert.That (result, Is.EqualTo ("abc"), "Aggregate seed");
-}
-
-// ===== NSMutableArray<T> =====
-
-[Test]
-public void NSMutableArray_First ()
-{
-using var arr = MakeMutableArray ("a", "b");
-Assert.That (arr.First ().ToString (), Is.EqualTo ("a"), "First");
-}
-
-[Test]
-public void NSMutableArray_First_Empty_Throws ()
-{
-using var arr = MakeMutableArray ();
-Assert.Throws<InvalidOperationException> (() => arr.First ());
-}
-
-[Test]
-public void NSMutableArray_FirstOrDefault_Empty ()
-{
-using var arr = MakeMutableArray ();
-Assert.That (arr.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
-}
-
-[Test]
-public void NSMutableArray_FirstOrDefault ()
-{
-using var arr = MakeMutableArray ("x", "y");
-Assert.That (arr.FirstOrDefault ()?.ToString (), Is.EqualTo ("x"), "FirstOrDefault");
-}
-
-[Test]
-public void NSMutableArray_Last ()
-{
-using var arr = MakeMutableArray ("a", "b", "c");
-Assert.That (arr.Last ().ToString (), Is.EqualTo ("c"), "Last");
-}
-
-[Test]
-public void NSMutableArray_LastOrDefault_Empty ()
-{
-using var arr = MakeMutableArray ();
-Assert.That (arr.LastOrDefault (), Is.Null, "LastOrDefault empty");
-}
-
-[Test]
-public void NSMutableArray_Single ()
-{
-using var arr = MakeMutableArray ("only");
-Assert.That (arr.Single ().ToString (), Is.EqualTo ("only"), "Single");
-}
-
-[Test]
-public void NSMutableArray_Single_Throws_OnMultiple ()
-{
-using var arr = MakeMutableArray ("a", "b");
-Assert.Throws<InvalidOperationException> (() => arr.Single ());
-}
-
-[Test]
-public void NSMutableArray_SingleOrDefault_Empty ()
-{
-using var arr = MakeMutableArray ();
-Assert.That (arr.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
-}
-
-[Test]
-public void NSMutableArray_ElementAt ()
-{
-using var arr = MakeMutableArray ("a", "b", "c");
-Assert.That (arr.ElementAt (1).ToString (), Is.EqualTo ("b"), "ElementAt 1");
-}
-
-[Test]
-public void NSMutableArray_ElementAtOrDefault ()
-{
-using var arr = MakeMutableArray ("a");
-Assert.That (arr.ElementAtOrDefault (0)?.ToString (), Is.EqualTo ("a"), "ElementAtOrDefault in range");
-Assert.That (arr.ElementAtOrDefault (10), Is.Null, "ElementAtOrDefault out of range");
-}
-
-[Test]
-public void NSMutableArray_Any ()
-{
-using var empty = MakeMutableArray ();
-Assert.That (empty.Any (), Is.False, "Any empty");
-using var arr = MakeMutableArray ("a");
-Assert.That (arr.Any (), Is.True, "Any non-empty");
-}
-
-[Test]
-public void NSMutableArray_All ()
-{
-using var arr = MakeMutableArray ("ab", "abc");
-Assert.That (arr.All (s => s.Length > 1), Is.True, "All true");
-}
-
-[Test]
-public void NSMutableArray_Count ()
-{
-using var arr = MakeMutableArray ("a", "b", "c");
-Assert.That (arr.Count (), Is.EqualTo (3), "Count");
-}
-
-[Test]
-public void NSMutableArray_LongCount ()
-{
-using var arr = MakeMutableArray ("a", "b");
-Assert.That (arr.LongCount (), Is.EqualTo (2L), "LongCount");
-}
-
-[Test]
-public void NSMutableArray_Where ()
-{
-using var arr = MakeMutableArray ("a", "bb", "ccc");
-var result = arr.Where (s => s.Length > 1).ToList ();
-Assert.That (result.Count, Is.EqualTo (2), "Where count");
-}
-
-[Test]
-public void NSMutableArray_Select ()
-{
-using var arr = MakeMutableArray ("hello", "world");
-var lengths = arr.Select (s => s.Length).ToList ();
-Assert.That (lengths [0], Is.EqualTo (5), "Select [0]");
-}
-
-[Test]
-public void NSMutableArray_OrderBy ()
-{
-using var arr = MakeMutableArray ("banana", "apple", "cherry");
-var sorted = arr.OrderBy (s => s.ToString ()).ToList ();
-Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
-}
-
-[Test]
-public void NSMutableArray_OrderByDescending ()
-{
-using var arr = MakeMutableArray ("banana", "apple", "cherry");
-var sorted = arr.OrderByDescending (s => s.ToString ()).ToList ();
-Assert.That (sorted [0].ToString (), Is.EqualTo ("cherry"), "OrderByDesc first");
-}
-
-[Test]
-public void NSMutableArray_Skip_Take ()
-{
-using var arr = MakeMutableArray ("a", "b", "c", "d");
-var sliced = arr.Skip (1).Take (2).ToList ();
-Assert.That (sliced.Count, Is.EqualTo (2), "Skip/Take count");
-}
-
-[Test]
-public void NSMutableArray_SkipWhile_TakeWhile ()
-{
-using var arr = MakeMutableArray ("a", "b", "c");
-var skipped = arr.SkipWhile (s => s.ToString () == "a").ToList ();
-Assert.That (skipped.Count, Is.EqualTo (2), "SkipWhile count");
-var taken = arr.TakeWhile (s => s.ToString () != "c").ToList ();
-Assert.That (taken.Count, Is.EqualTo (2), "TakeWhile count");
-}
-
-[Test]
-public void NSMutableArray_Distinct ()
-{
-using var arr = MakeMutableArray ("a", "a", "b");
-var distinct = arr.Distinct ().ToList ();
-Assert.That (distinct.Count, Is.EqualTo (2), "Distinct count");
-}
-
-[Test]
-public void NSMutableArray_Reverse ()
-{
-using var arr = MakeMutableArray ("a", "b", "c");
-var reversed = arr.Reverse ().ToList ();
-Assert.That (reversed [0].ToString (), Is.EqualTo ("c"), "Reverse [0]");
-}
-
-[Test]
-public void NSMutableArray_Concat ()
-{
-using var arr = MakeMutableArray ("a");
-var all = arr.Concat (new [] { S ("b") }).ToList ();
-Assert.That (all.Count, Is.EqualTo (2), "Concat count");
-}
-
-[Test]
-public void NSMutableArray_ToList ()
-{
-using var arr = MakeMutableArray ("a", "b");
-var list = arr.ToList ();
-Assert.That (list.Count, Is.EqualTo (2), "ToList count");
-}
-
-[Test]
-public void NSMutableArray_ToArray ()
-{
-using var arr = MakeMutableArray ("a", "b");
-var result = arr.ToArray ();
-Assert.That (result.Length, Is.EqualTo (2), "ToArray length");
-}
-
-[Test]
-public void NSMutableArray_Aggregate ()
-{
-using var arr = MakeMutableArray ("a", "b", "c");
-var result = arr.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
-Assert.That (result.ToString (), Is.EqualTo ("abc"), "Aggregate");
-}
-
-[Test]
-public void NSMutableArray_Aggregate_Seed ()
-{
-using var arr = MakeMutableArray ("a", "b", "c");
-var result = arr.Aggregate (0, (acc, s) => acc + s.Length);
-Assert.That (result, Is.EqualTo (3), "Aggregate seed");
-}
-
-// ===== NSOrderedSet<T> =====
-
-[Test]
-public void NSOrderedSet_First ()
-{
-using var set = MakeOrderedSet ("a", "b", "c");
-Assert.That (set.First ().ToString (), Is.EqualTo ("a"), "First");
-}
-
-[Test]
-public void NSOrderedSet_First_Predicate ()
-{
-using var set = MakeOrderedSet ("a", "b", "c");
-Assert.That (set.First (s => s.ToString () == "c").ToString (), Is.EqualTo ("c"), "First predicate");
-}
-
-[Test]
-public void NSOrderedSet_First_Empty_Throws ()
-{
-using var set = MakeOrderedSet ();
-Assert.Throws<InvalidOperationException> (() => set.First ());
-}
-
-[Test]
-public void NSOrderedSet_FirstOrDefault_Empty ()
-{
-using var set = MakeOrderedSet ();
-Assert.That (set.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
-}
-
-[Test]
-public void NSOrderedSet_FirstOrDefault ()
-{
-using var set = MakeOrderedSet ("x", "y");
-Assert.That (set.FirstOrDefault ()?.ToString (), Is.EqualTo ("x"), "FirstOrDefault");
-}
-
-[Test]
-public void NSOrderedSet_Last ()
-{
-using var set = MakeOrderedSet ("a", "b", "c");
-Assert.That (set.Last ().ToString (), Is.EqualTo ("c"), "Last");
-}
-
-[Test]
-public void NSOrderedSet_Last_Predicate ()
-{
-using var set = MakeOrderedSet ("a", "b", "c");
-Assert.That (set.Last (s => s.ToString () != "c").ToString (), Is.EqualTo ("b"), "Last predicate");
-}
-
-[Test]
-public void NSOrderedSet_Last_Empty_Throws ()
-{
-using var set = MakeOrderedSet ();
-Assert.Throws<InvalidOperationException> (() => set.Last ());
-}
-
-[Test]
-public void NSOrderedSet_LastOrDefault_Empty ()
-{
-using var set = MakeOrderedSet ();
-Assert.That (set.LastOrDefault (), Is.Null, "LastOrDefault empty");
-}
-
-[Test]
-public void NSOrderedSet_Single ()
-{
-using var set = MakeOrderedSet ("only");
-Assert.That (set.Single ().ToString (), Is.EqualTo ("only"), "Single");
-}
-
-[Test]
-public void NSOrderedSet_Single_Throws_OnMultiple ()
-{
-using var set = MakeOrderedSet ("a", "b");
-Assert.Throws<InvalidOperationException> (() => set.Single ());
-}
-
-[Test]
-public void NSOrderedSet_SingleOrDefault_Empty ()
-{
-using var set = MakeOrderedSet ();
-Assert.That (set.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
-}
-
-[Test]
-public void NSOrderedSet_SingleOrDefault_Predicate ()
-{
-using var set = MakeOrderedSet ("a", "b");
-Assert.That (set.SingleOrDefault (s => s.ToString () == "a")?.ToString (), Is.EqualTo ("a"), "SingleOrDefault predicate match");
-}
-
-[Test]
-public void NSOrderedSet_ElementAt ()
-{
-using var set = MakeOrderedSet ("a", "b", "c");
-Assert.That (set.ElementAt (1).ToString (), Is.EqualTo ("b"), "ElementAt 1");
-}
-
-[Test]
-public void NSOrderedSet_ElementAtOrDefault ()
-{
-using var set = MakeOrderedSet ("a");
-Assert.That (set.ElementAtOrDefault (0)?.ToString (), Is.EqualTo ("a"), "in range");
-Assert.That (set.ElementAtOrDefault (5), Is.Null, "out of range");
-}
-
-[Test]
-public void NSOrderedSet_Any ()
-{
-using var empty = MakeOrderedSet ();
-Assert.That (empty.Any (), Is.False, "Any empty");
-using var set = MakeOrderedSet ("a");
-Assert.That (set.Any (), Is.True, "Any non-empty");
-Assert.That (set.Any (s => s.ToString () == "a"), Is.True, "Any predicate true");
-Assert.That (set.Any (s => s.ToString () == "z"), Is.False, "Any predicate false");
-}
-
-[Test]
-public void NSOrderedSet_All ()
-{
-using var set = MakeOrderedSet ("ab", "abc");
-Assert.That (set.All (s => s.Length > 1), Is.True, "All true");
-Assert.That (set.All (s => s.Length > 2), Is.False, "All false");
-}
-
-[Test]
-public void NSOrderedSet_Count ()
-{
-using var set = MakeOrderedSet ("a", "b", "c");
-Assert.That (set.Count (), Is.EqualTo (3), "Count");
-Assert.That (set.Count (s => s.ToString () == "a"), Is.EqualTo (1), "Count predicate");
-}
-
-[Test]
-public void NSOrderedSet_LongCount ()
-{
-using var set = MakeOrderedSet ("a", "b");
-Assert.That (set.LongCount (), Is.EqualTo (2L), "LongCount");
-}
-
-[Test]
-public void NSOrderedSet_Where ()
-{
-using var set = MakeOrderedSet ("a", "bb", "ccc");
-var result = set.Where (s => s.Length > 1).ToList ();
-Assert.That (result.Count, Is.EqualTo (2), "Where count");
-}
-
-[Test]
-public void NSOrderedSet_Where_Index ()
-{
-using var set = MakeOrderedSet ("a", "b", "c");
-var result = set.Where ((s, i) => i % 2 == 0).ToList ();
-Assert.That (result.Count, Is.EqualTo (2), "Where index count");
-}
-
-[Test]
-public void NSOrderedSet_Select ()
-{
-using var set = MakeOrderedSet ("hello", "world");
-var lengths = set.Select (s => s.Length).ToList ();
-Assert.That (lengths [0], Is.EqualTo (5), "Select [0]");
-}
-
-[Test]
-public void NSOrderedSet_Select_Index ()
-{
-using var set = MakeOrderedSet ("a", "b");
-var indexed = set.Select ((s, i) => $"{i}:{s}").ToList ();
-Assert.That (indexed [0], Is.EqualTo ("0:a"), "Select index 0");
-}
-
-[Test]
-public void NSOrderedSet_OrderBy ()
-{
-using var set = MakeOrderedSet ("banana", "apple", "cherry");
-var sorted = set.OrderBy (s => s.ToString ()).ToList ();
-Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
-}
-
-[Test]
-public void NSOrderedSet_OrderByDescending ()
-{
-using var set = MakeOrderedSet ("banana", "apple", "cherry");
-var sorted = set.OrderByDescending (s => s.ToString ()).ToList ();
-Assert.That (sorted [0].ToString (), Is.EqualTo ("cherry"), "OrderByDesc first");
-}
-
-[Test]
-public void NSOrderedSet_Skip_Take ()
-{
-using var set = MakeOrderedSet ("a", "b", "c", "d");
-var sliced = set.Skip (1).Take (2).ToList ();
-Assert.That (sliced.Count, Is.EqualTo (2), "Skip/Take count");
-Assert.That (sliced [0].ToString (), Is.EqualTo ("b"), "Skip/Take [0]");
-}
-
-[Test]
-public void NSOrderedSet_SkipWhile_TakeWhile ()
-{
-using var set = MakeOrderedSet ("a", "b", "c");
-var skipped = set.SkipWhile (s => s.ToString () == "a").ToList ();
-Assert.That (skipped.Count, Is.EqualTo (2), "SkipWhile count");
-var taken = set.TakeWhile (s => s.ToString () != "c").ToList ();
-Assert.That (taken.Count, Is.EqualTo (2), "TakeWhile count");
-}
-
-[Test]
-public void NSOrderedSet_Distinct ()
-{
-using var set = MakeOrderedSet ("a", "b");
-var distinct = set.Distinct ().ToList ();
-Assert.That (distinct.Count, Is.EqualTo (2), "Distinct count");
-}
-
-[Test]
-public void NSOrderedSet_Reverse ()
-{
-using var set = MakeOrderedSet ("a", "b", "c");
-var reversed = set.Reverse ().ToList ();
-Assert.That (reversed [0].ToString (), Is.EqualTo ("c"), "Reverse [0]");
-Assert.That (reversed [2].ToString (), Is.EqualTo ("a"), "Reverse [2]");
-}
-
-[Test]
-public void NSOrderedSet_Concat ()
-{
-using var set = MakeOrderedSet ("a", "b");
-var all = set.Concat (new [] { S ("c") }).ToList ();
-Assert.That (all.Count, Is.EqualTo (3), "Concat count");
-}
-
-[Test]
-public void NSOrderedSet_ToList ()
-{
-using var set = MakeOrderedSet ("a", "b");
-var list = set.ToList ();
-Assert.That (list.Count, Is.EqualTo (2), "ToList count");
-}
-
-[Test]
-public void NSOrderedSet_ToArray ()
-{
-using var set = MakeOrderedSet ("a", "b");
-var arr = set.ToArray ();
-Assert.That (arr.Length, Is.EqualTo (2), "ToArray length");
-}
-
-[Test]
-public void NSOrderedSet_Aggregate ()
-{
-using var set = MakeOrderedSet ("a", "b", "c");
-var result = set.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
-Assert.That (result.ToString (), Is.EqualTo ("abc"), "Aggregate");
-}
-
-[Test]
-public void NSOrderedSet_Aggregate_Seed ()
-{
-using var set = MakeOrderedSet ("a", "b", "c");
-var result = set.Aggregate ("", (acc, s) => acc + s.ToString ());
-Assert.That (result, Is.EqualTo ("abc"), "Aggregate seed");
-}
-
-// ===== NSMutableOrderedSet<T> =====
-
-[Test]
-public void NSMutableOrderedSet_First ()
-{
-using var set = MakeMutableOrderedSet ("a", "b", "c");
-Assert.That (set.First ().ToString (), Is.EqualTo ("a"), "First");
-}
-
-[Test]
-public void NSMutableOrderedSet_First_Empty_Throws ()
-{
-using var set = MakeMutableOrderedSet ();
-Assert.Throws<InvalidOperationException> (() => set.First ());
-}
-
-[Test]
-public void NSMutableOrderedSet_FirstOrDefault_Empty ()
-{
-using var set = MakeMutableOrderedSet ();
-Assert.That (set.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
-}
-
-[Test]
-public void NSMutableOrderedSet_FirstOrDefault ()
-{
-using var set = MakeMutableOrderedSet ("x", "y");
-Assert.That (set.FirstOrDefault ()?.ToString (), Is.EqualTo ("x"), "FirstOrDefault");
-}
-
-[Test]
-public void NSMutableOrderedSet_FirstOrDefault_Predicate ()
-{
-using var set = MakeMutableOrderedSet ("a", "b", "c");
-Assert.That (set.FirstOrDefault (s => s.ToString () == "b")?.ToString (), Is.EqualTo ("b"), "FirstOrDefault predicate match");
-Assert.That (set.FirstOrDefault (s => s.ToString () == "z"), Is.Null, "FirstOrDefault predicate no match");
-}
-
-[Test]
-public void NSMutableOrderedSet_Last ()
-{
-using var set = MakeMutableOrderedSet ("a", "b", "c");
-Assert.That (set.Last ().ToString (), Is.EqualTo ("c"), "Last");
-}
-
-[Test]
-public void NSMutableOrderedSet_LastOrDefault_Empty ()
-{
-using var set = MakeMutableOrderedSet ();
-Assert.That (set.LastOrDefault (), Is.Null, "LastOrDefault empty");
-}
-
-[Test]
-public void NSMutableOrderedSet_Single ()
-{
-using var set = MakeMutableOrderedSet ("only");
-Assert.That (set.Single ().ToString (), Is.EqualTo ("only"), "Single");
-}
-
-[Test]
-public void NSMutableOrderedSet_Single_Throws_OnMultiple ()
-{
-using var set = MakeMutableOrderedSet ("a", "b");
-Assert.Throws<InvalidOperationException> (() => set.Single ());
-}
-
-[Test]
-public void NSMutableOrderedSet_SingleOrDefault_Empty ()
-{
-using var set = MakeMutableOrderedSet ();
-Assert.That (set.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
-}
-
-[Test]
-public void NSMutableOrderedSet_ElementAt ()
-{
-using var set = MakeMutableOrderedSet ("a", "b", "c");
-Assert.That (set.ElementAt (2).ToString (), Is.EqualTo ("c"), "ElementAt 2");
-}
-
-[Test]
-public void NSMutableOrderedSet_ElementAtOrDefault ()
-{
-using var set = MakeMutableOrderedSet ("a");
-Assert.That (set.ElementAtOrDefault (0)?.ToString (), Is.EqualTo ("a"), "in range");
-Assert.That (set.ElementAtOrDefault (5), Is.Null, "out of range");
-}
-
-[Test]
-public void NSMutableOrderedSet_Any ()
-{
-using var empty = MakeMutableOrderedSet ();
-Assert.That (empty.Any (), Is.False, "Any empty");
-using var set = MakeMutableOrderedSet ("a");
-Assert.That (set.Any (), Is.True, "Any non-empty");
-}
-
-[Test]
-public void NSMutableOrderedSet_All ()
-{
-using var set = MakeMutableOrderedSet ("ab", "abc");
-Assert.That (set.All (s => s.Length > 1), Is.True, "All true");
-}
-
-[Test]
-public void NSMutableOrderedSet_Count ()
-{
-using var set = MakeMutableOrderedSet ("a", "b", "c");
-Assert.That (set.Count (), Is.EqualTo (3), "Count");
-Assert.That (set.Count (s => s.ToString () == "a"), Is.EqualTo (1), "Count predicate");
-}
-
-[Test]
-public void NSMutableOrderedSet_LongCount ()
-{
-using var set = MakeMutableOrderedSet ("a", "b");
-Assert.That (set.LongCount (), Is.EqualTo (2L), "LongCount");
-}
-
-[Test]
-public void NSMutableOrderedSet_Where ()
-{
-using var set = MakeMutableOrderedSet ("a", "bb", "ccc");
-var result = set.Where (s => s.Length > 1).ToList ();
-Assert.That (result.Count, Is.EqualTo (2), "Where count");
-}
-
-[Test]
-public void NSMutableOrderedSet_Select ()
-{
-using var set = MakeMutableOrderedSet ("hello", "world");
-var lengths = set.Select (s => s.Length).ToList ();
-Assert.That (lengths [0], Is.EqualTo (5), "Select [0]");
-}
-
-[Test]
-public void NSMutableOrderedSet_OrderBy ()
-{
-using var set = MakeMutableOrderedSet ("banana", "apple", "cherry");
-var sorted = set.OrderBy (s => s.ToString ()).ToList ();
-Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
-}
-
-[Test]
-public void NSMutableOrderedSet_OrderByDescending ()
-{
-using var set = MakeMutableOrderedSet ("banana", "apple", "cherry");
-var sorted = set.OrderByDescending (s => s.ToString ()).ToList ();
-Assert.That (sorted [0].ToString (), Is.EqualTo ("cherry"), "OrderByDesc first");
-}
-
-[Test]
-public void NSMutableOrderedSet_Skip_Take ()
-{
-using var set = MakeMutableOrderedSet ("a", "b", "c", "d");
-var sliced = set.Skip (1).Take (2).ToList ();
-Assert.That (sliced.Count, Is.EqualTo (2), "Skip/Take count");
-Assert.That (sliced [0].ToString (), Is.EqualTo ("b"), "Skip/Take [0]");
-}
-
-[Test]
-public void NSMutableOrderedSet_SkipWhile_TakeWhile ()
-{
-using var set = MakeMutableOrderedSet ("a", "b", "c");
-var skipped = set.SkipWhile (s => s.ToString () == "a").ToList ();
-Assert.That (skipped.Count, Is.EqualTo (2), "SkipWhile count");
-var taken = set.TakeWhile (s => s.ToString () != "c").ToList ();
-Assert.That (taken.Count, Is.EqualTo (2), "TakeWhile count");
-}
-
-[Test]
-public void NSMutableOrderedSet_Distinct ()
-{
-using var set = MakeMutableOrderedSet ("a", "b");
-var distinct = set.Distinct ().ToList ();
-Assert.That (distinct.Count, Is.EqualTo (2), "Distinct count");
-}
-
-[Test]
-public void NSMutableOrderedSet_Reverse ()
-{
-using var set = MakeMutableOrderedSet ("a", "b", "c");
-var reversed = set.Reverse ().ToList ();
-Assert.That (reversed [0].ToString (), Is.EqualTo ("c"), "Reverse [0]");
-Assert.That (reversed [2].ToString (), Is.EqualTo ("a"), "Reverse [2]");
-}
-
-[Test]
-public void NSMutableOrderedSet_Concat ()
-{
-using var set = MakeMutableOrderedSet ("a", "b");
-var all = set.Concat (new [] { S ("c") }).ToList ();
-Assert.That (all.Count, Is.EqualTo (3), "Concat count");
-}
-
-[Test]
-public void NSMutableOrderedSet_ToList ()
-{
-using var set = MakeMutableOrderedSet ("a", "b");
-var list = set.ToList ();
-Assert.That (list.Count, Is.EqualTo (2), "ToList count");
-}
-
-[Test]
-public void NSMutableOrderedSet_ToArray ()
-{
-using var set = MakeMutableOrderedSet ("a", "b");
-var arr = set.ToArray ();
-Assert.That (arr.Length, Is.EqualTo (2), "ToArray length");
-}
-
-[Test]
-public void NSMutableOrderedSet_Aggregate ()
-{
-using var set = MakeMutableOrderedSet ("a", "b", "c");
-var result = set.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
-Assert.That (result.ToString (), Is.EqualTo ("abc"), "Aggregate");
-}
-
-[Test]
-public void NSMutableOrderedSet_Aggregate_Seed ()
-{
-using var set = MakeMutableOrderedSet ("a", "b", "c");
-var result = set.Aggregate ("", (acc, s) => acc + s.ToString ());
-Assert.That (result, Is.EqualTo ("abc"), "Aggregate seed");
-}
-}
+	[TestFixture]
+	[Preserve (AllMembers = true)]
+	public class NSCollectionLinqTest {
+
+		// ----- helpers -----
+
+		static NSString S (string s) => (NSString) s;
+
+		static NSSet<NSString> MakeSet (params string [] items)
+		{
+			return new NSSet<NSString> (items.Select (S).ToArray ());
+		}
+
+		static NSMutableSet<NSString> MakeMutableSet (params string [] items)
+		{
+			return new NSMutableSet<NSString> (items.Select (S).ToArray ());
+		}
+
+		static NSArray<NSString> MakeArray (params string [] items)
+		{
+			return NSArray<NSString>.FromNSObjects (items.Select (S).ToArray ());
+		}
+
+		static NSMutableArray<NSString> MakeMutableArray (params string [] items)
+		{
+			var arr = new NSMutableArray<NSString> ();
+			foreach (var s in items)
+				arr.Add (S (s));
+			return arr;
+		}
+
+		static NSOrderedSet<NSString> MakeOrderedSet (params string [] items)
+		{
+			return new NSOrderedSet<NSString> (items.Select (S).ToArray ());
+		}
+
+		static NSMutableOrderedSet<NSString> MakeMutableOrderedSet (params string [] items)
+		{
+			var set = new NSMutableOrderedSet<NSString> ();
+			foreach (var s in items)
+				set.Add (S (s));
+			return set;
+		}
+
+		// ===== NSSet<T> =====
+
+		[Test]
+		public void NSSet_First ()
+		{
+			using var set = MakeSet ("a");
+			var first = set.First ();
+			Assert.That (first.ToString (), Is.EqualTo ("a"), "First");
+		}
+
+		[Test]
+		public void NSSet_First_Predicate ()
+		{
+			using var set = MakeSet ("a", "b", "c");
+			var found = set.First (s => s.ToString () == "b");
+			Assert.That (found.ToString (), Is.EqualTo ("b"), "First predicate");
+		}
+
+		[Test]
+		public void NSSet_First_Empty_Throws ()
+		{
+			using var set = MakeSet ();
+			Assert.Throws<InvalidOperationException> (() => set.First ());
+		}
+
+		[Test]
+		public void NSSet_FirstOrDefault_Empty ()
+		{
+			using var set = MakeSet ();
+			Assert.That (set.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
+		}
+
+		[Test]
+		public void NSSet_FirstOrDefault ()
+		{
+			using var set = MakeSet ("x");
+			Assert.That (set.FirstOrDefault (), Is.Not.Null, "FirstOrDefault");
+		}
+
+		[Test]
+		public void NSSet_FirstOrDefault_Predicate_NoMatch ()
+		{
+			using var set = MakeSet ("a", "b");
+			Assert.That (set.FirstOrDefault (s => s.ToString () == "z"), Is.Null, "no match");
+		}
+
+		[Test]
+		public void NSSet_Last ()
+		{
+			using var set = MakeSet ("a");
+			var last = set.Last ();
+			Assert.That (last.ToString (), Is.EqualTo ("a"), "Last");
+		}
+
+		[Test]
+		public void NSSet_Last_Predicate ()
+		{
+			using var set = MakeSet ("a", "b", "c");
+			var found = set.Last (s => s.ToString () != "c");
+			Assert.That (found, Is.Not.Null, "Last predicate not null");
+		}
+
+		[Test]
+		public void NSSet_Last_Empty_Throws ()
+		{
+			using var set = MakeSet ();
+			Assert.Throws<InvalidOperationException> (() => set.Last ());
+		}
+
+		[Test]
+		public void NSSet_LastOrDefault_Empty ()
+		{
+			using var set = MakeSet ();
+			Assert.That (set.LastOrDefault (), Is.Null, "LastOrDefault empty");
+		}
+
+		[Test]
+		public void NSSet_LastOrDefault_Predicate_NoMatch ()
+		{
+			using var set = MakeSet ("a");
+			Assert.That (set.LastOrDefault (s => s.ToString () == "z"), Is.Null, "LastOrDefault no match");
+		}
+
+		[Test]
+		public void NSSet_Single ()
+		{
+			using var set = MakeSet ("only");
+			Assert.That (set.Single ().ToString (), Is.EqualTo ("only"), "Single");
+		}
+
+		[Test]
+		public void NSSet_Single_Throws_OnMultiple ()
+		{
+			using var set = MakeSet ("a", "b");
+			Assert.Throws<InvalidOperationException> (() => set.Single ());
+		}
+
+		[Test]
+		public void NSSet_SingleOrDefault_Empty ()
+		{
+			using var set = MakeSet ();
+			Assert.That (set.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
+		}
+
+		[Test]
+		public void NSSet_SingleOrDefault_Predicate ()
+		{
+			using var set = MakeSet ("a", "b");
+			Assert.That (set.SingleOrDefault (s => s.ToString () == "a")?.ToString (), Is.EqualTo ("a"), "SingleOrDefault predicate");
+		}
+
+		[Test]
+		public void NSSet_Any_Empty ()
+		{
+			using var set = MakeSet ();
+			Assert.That (set.Any (), Is.False, "Any empty");
+		}
+
+		[Test]
+		public void NSSet_Any_NonEmpty ()
+		{
+			using var set = MakeSet ("a");
+			Assert.That (set.Any (), Is.True, "Any non-empty");
+		}
+
+		[Test]
+		public void NSSet_Any_Predicate ()
+		{
+			using var set = MakeSet ("a", "b");
+			Assert.That (set.Any (s => s.ToString () == "b"), Is.True, "Any predicate true");
+			Assert.That (set.Any (s => s.ToString () == "z"), Is.False, "Any predicate false");
+		}
+
+		[Test]
+		public void NSSet_All ()
+		{
+			using var set = MakeSet ("ab", "abc");
+			Assert.That (set.All (s => s.Length > 1), Is.True, "All true");
+			Assert.That (set.All (s => s.Length > 2), Is.False, "All false");
+		}
+
+		[Test]
+		public void NSSet_Count ()
+		{
+			using var set = MakeSet ("a", "b", "c");
+			Assert.That (set.Count (), Is.EqualTo (3), "Count");
+			Assert.That (set.Count (s => s.ToString () == "a"), Is.EqualTo (1), "Count predicate");
+		}
+
+		[Test]
+		public void NSSet_LongCount ()
+		{
+			using var set = MakeSet ("a", "b");
+			Assert.That (set.LongCount (), Is.EqualTo (2L), "LongCount");
+			Assert.That (set.LongCount (s => s.ToString () == "a"), Is.EqualTo (1L), "LongCount predicate");
+		}
+
+		[Test]
+		public void NSSet_Where ()
+		{
+			using var set = MakeSet ("a", "bb", "ccc");
+			var result = set.Where (s => s.Length > 1).ToList ();
+			Assert.That (result.Count, Is.EqualTo (2), "Where count");
+		}
+
+		[Test]
+		public void NSSet_Where_Index ()
+		{
+			using var arr = MakeOrderedSet ("a", "b", "c");
+			var result = arr.Where ((s, i) => i % 2 == 0).ToList ();
+			Assert.That (result.Count, Is.EqualTo (2), "Where index count");
+		}
+
+		[Test]
+		public void NSSet_Select ()
+		{
+			using var set = MakeSet ("hello");
+			var lengths = set.Select (s => s.Length).ToList ();
+			Assert.That (lengths, Contains.Item (5), "Select length");
+		}
+
+		[Test]
+		public void NSSet_Select_Index ()
+		{
+			using var arr = MakeOrderedSet ("a", "b", "c");
+			var indexed = arr.Select ((s, i) => $"{i}:{s}").ToList ();
+			Assert.That (indexed [0], Is.EqualTo ("0:a"), "Select index 0");
+			Assert.That (indexed [1], Is.EqualTo ("1:b"), "Select index 1");
+		}
+
+		[Test]
+		public void NSSet_OrderBy ()
+		{
+			using var set = MakeSet ("banana", "apple", "cherry");
+			var sorted = set.OrderBy (s => s.ToString ()).ToList ();
+			Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
+			Assert.That (sorted [2].ToString (), Is.EqualTo ("cherry"), "OrderBy last");
+		}
+
+		[Test]
+		public void NSSet_OrderByDescending ()
+		{
+			using var set = MakeSet ("banana", "apple", "cherry");
+			var sorted = set.OrderByDescending (s => s.ToString ()).ToList ();
+			Assert.That (sorted [0].ToString (), Is.EqualTo ("cherry"), "OrderByDesc first");
+		}
+
+		[Test]
+		public void NSSet_Distinct ()
+		{
+			using var set = MakeSet ("a", "b", "b");
+			// NSSet already ensures uniqueness, but verify Distinct works
+			var distinct = set.Distinct ().ToList ();
+			Assert.That (distinct.Count, Is.EqualTo (2), "Distinct count");
+		}
+
+		[Test]
+		public void NSSet_Reverse ()
+		{
+			using var arr = MakeOrderedSet ("a", "b", "c");
+			var reversed = arr.Reverse ().ToList ();
+			Assert.That (reversed [0].ToString (), Is.EqualTo ("c"), "Reverse first");
+			Assert.That (reversed [2].ToString (), Is.EqualTo ("a"), "Reverse last");
+		}
+
+		[Test]
+		public void NSSet_Concat ()
+		{
+			using var set = MakeSet ("a", "b");
+			var extra = new [] { S ("c"), S ("d") };
+			var all = set.Concat (extra).ToList ();
+			Assert.That (all.Count, Is.EqualTo (4), "Concat count");
+		}
+
+		[Test]
+		public void NSSet_Skip_Take ()
+		{
+			using var arr = MakeOrderedSet ("a", "b", "c", "d");
+			var sliced = arr.Skip (1).Take (2).ToList ();
+			Assert.That (sliced.Count, Is.EqualTo (2), "Skip/Take count");
+			Assert.That (sliced [0].ToString (), Is.EqualTo ("b"), "Skip/Take first");
+		}
+
+		[Test]
+		public void NSSet_SkipWhile_TakeWhile ()
+		{
+			using var arr = MakeOrderedSet ("a", "b", "c");
+			var skipped = arr.SkipWhile (s => s.ToString () == "a").ToList ();
+			Assert.That (skipped.Count, Is.EqualTo (2), "SkipWhile count");
+
+			var taken = arr.TakeWhile (s => s.ToString () != "c").ToList ();
+			Assert.That (taken.Count, Is.EqualTo (2), "TakeWhile count");
+		}
+
+		[Test]
+		public void NSSet_ElementAt ()
+		{
+			using var arr = MakeOrderedSet ("a", "b", "c");
+			Assert.That (arr.ElementAt (1).ToString (), Is.EqualTo ("b"), "ElementAt");
+		}
+
+		[Test]
+		public void NSSet_ElementAtOrDefault ()
+		{
+			using var arr = MakeOrderedSet ("a", "b");
+			Assert.That (arr.ElementAtOrDefault (0), Is.Not.Null, "ElementAtOrDefault in range");
+			Assert.That (arr.ElementAtOrDefault (99), Is.Null, "ElementAtOrDefault out of range");
+		}
+
+		[Test]
+		public void NSSet_ToList ()
+		{
+			using var set = MakeSet ("a", "b");
+			var list = set.ToList ();
+			Assert.That (list, Is.TypeOf<List<NSString>> (), "ToList type");
+			Assert.That (list.Count, Is.EqualTo (2), "ToList count");
+		}
+
+		[Test]
+		public void NSSet_ToArray ()
+		{
+			using var set = MakeSet ("a", "b");
+			var arr = set.ToArray ();
+			Assert.That (arr, Is.TypeOf<NSString []> (), "ToArray type");
+			Assert.That (arr.Length, Is.EqualTo (2), "ToArray length");
+		}
+
+		[Test]
+		public void NSSet_Aggregate ()
+		{
+			using var arr = MakeOrderedSet ("a", "b", "c");
+			var result = arr.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
+			Assert.That (result.ToString (), Is.EqualTo ("abc"), "Aggregate");
+		}
+
+		[Test]
+		public void NSSet_Aggregate_Seed ()
+		{
+			using var arr = MakeOrderedSet ("a", "b", "c");
+			var result = arr.Aggregate ("", (acc, s) => acc + s.ToString ());
+			Assert.That (result, Is.EqualTo ("abc"), "Aggregate seed");
+		}
+
+		// ===== NSMutableSet<T> =====
+
+		[Test]
+		public void NSMutableSet_First ()
+		{
+			using var set = MakeMutableSet ("a");
+			Assert.That (set.First ().ToString (), Is.EqualTo ("a"), "First");
+		}
+
+		[Test]
+		public void NSMutableSet_FirstOrDefault_Empty ()
+		{
+			using var set = MakeMutableSet ();
+			Assert.That (set.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
+		}
+
+		[Test]
+		public void NSMutableSet_Last ()
+		{
+			using var set = MakeMutableSet ("a");
+			Assert.That (set.Last ().ToString (), Is.EqualTo ("a"), "Last");
+		}
+
+		[Test]
+		public void NSMutableSet_LastOrDefault_Empty ()
+		{
+			using var set = MakeMutableSet ();
+			Assert.That (set.LastOrDefault (), Is.Null, "LastOrDefault empty");
+		}
+
+		[Test]
+		public void NSMutableSet_Single ()
+		{
+			using var set = MakeMutableSet ("only");
+			Assert.That (set.Single ().ToString (), Is.EqualTo ("only"), "Single");
+		}
+
+		[Test]
+		public void NSMutableSet_SingleOrDefault_Empty ()
+		{
+			using var set = MakeMutableSet ();
+			Assert.That (set.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
+		}
+
+		[Test]
+		public void NSMutableSet_Any ()
+		{
+			using var set = MakeMutableSet ();
+			Assert.That (set.Any (), Is.False, "Any empty");
+			using var set2 = MakeMutableSet ("a");
+			Assert.That (set2.Any (), Is.True, "Any non-empty");
+		}
+
+		[Test]
+		public void NSMutableSet_All ()
+		{
+			using var set = MakeMutableSet ("ab", "abc");
+			Assert.That (set.All (s => s.Length > 1), Is.True, "All true");
+		}
+
+		[Test]
+		public void NSMutableSet_Count ()
+		{
+			using var set = MakeMutableSet ("a", "b", "c");
+			Assert.That (set.Count (), Is.EqualTo (3), "Count");
+		}
+
+		[Test]
+		public void NSMutableSet_LongCount ()
+		{
+			using var set = MakeMutableSet ("a", "b");
+			Assert.That (set.LongCount (), Is.EqualTo (2L), "LongCount");
+		}
+
+		[Test]
+		public void NSMutableSet_Where ()
+		{
+			using var set = MakeMutableSet ("a", "bb", "ccc");
+			var result = set.Where (s => s.Length > 1).ToList ();
+			Assert.That (result.Count, Is.EqualTo (2), "Where count");
+		}
+
+		[Test]
+		public void NSMutableSet_Select ()
+		{
+			using var set = MakeMutableSet ("hello");
+			var lengths = set.Select (s => s.Length).ToList ();
+			Assert.That (lengths, Contains.Item (5), "Select length");
+		}
+
+		[Test]
+		public void NSMutableSet_OrderBy ()
+		{
+			using var set = MakeMutableSet ("banana", "apple", "cherry");
+			var sorted = set.OrderBy (s => s.ToString ()).ToList ();
+			Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
+		}
+
+		[Test]
+		public void NSMutableSet_Skip_Take ()
+		{
+			using var arr = MakeOrderedSet ("a", "b", "c", "d");
+			var sliced = arr.Skip (1).Take (2).ToList ();
+			Assert.That (sliced.Count, Is.EqualTo (2), "Skip/Take count");
+		}
+
+		[Test]
+		public void NSMutableSet_ToList ()
+		{
+			using var set = MakeMutableSet ("a", "b");
+			var list = set.ToList ();
+			Assert.That (list.Count, Is.EqualTo (2), "ToList count");
+		}
+
+		[Test]
+		public void NSMutableSet_ToArray ()
+		{
+			using var set = MakeMutableSet ("a", "b");
+			var arr = set.ToArray ();
+			Assert.That (arr.Length, Is.EqualTo (2), "ToArray length");
+		}
+
+		[Test]
+		public void NSMutableSet_Aggregate ()
+		{
+			using var set = MakeMutableSet ("a");
+			var result = set.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
+			Assert.That (result.ToString (), Is.EqualTo ("a"), "Aggregate");
+		}
+
+		// ===== NSArray<T> =====
+
+		[Test]
+		public void NSArray_First ()
+		{
+			using var arr = MakeArray ("a", "b", "c");
+			Assert.That (arr.First ().ToString (), Is.EqualTo ("a"), "First");
+		}
+
+		[Test]
+		public void NSArray_First_Predicate ()
+		{
+			using var arr = MakeArray ("a", "b", "c");
+			Assert.That (arr.First (s => s.ToString () == "b").ToString (), Is.EqualTo ("b"), "First predicate");
+		}
+
+		[Test]
+		public void NSArray_First_Empty_Throws ()
+		{
+			using var arr = MakeArray ();
+			Assert.Throws<InvalidOperationException> (() => arr.First ());
+		}
+
+		[Test]
+		public void NSArray_FirstOrDefault_Empty ()
+		{
+			using var arr = MakeArray ();
+			Assert.That (arr.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
+		}
+
+		[Test]
+		public void NSArray_FirstOrDefault ()
+		{
+			using var arr = MakeArray ("x", "y");
+			Assert.That (arr.FirstOrDefault ()?.ToString (), Is.EqualTo ("x"), "FirstOrDefault");
+		}
+
+		[Test]
+		public void NSArray_FirstOrDefault_Predicate ()
+		{
+			using var arr = MakeArray ("a", "b", "c");
+			Assert.That (arr.FirstOrDefault (s => s.ToString () == "b")?.ToString (), Is.EqualTo ("b"), "FirstOrDefault predicate match");
+			Assert.That (arr.FirstOrDefault (s => s.ToString () == "z"), Is.Null, "FirstOrDefault predicate no match");
+		}
+
+		[Test]
+		public void NSArray_Last ()
+		{
+			using var arr = MakeArray ("a", "b", "c");
+			Assert.That (arr.Last ().ToString (), Is.EqualTo ("c"), "Last");
+		}
+
+		[Test]
+		public void NSArray_Last_Predicate ()
+		{
+			using var arr = MakeArray ("a", "b", "c");
+			Assert.That (arr.Last (s => s.ToString () != "c").ToString (), Is.EqualTo ("b"), "Last predicate");
+		}
+
+		[Test]
+		public void NSArray_Last_Empty_Throws ()
+		{
+			using var arr = MakeArray ();
+			Assert.Throws<InvalidOperationException> (() => arr.Last ());
+		}
+
+		[Test]
+		public void NSArray_LastOrDefault_Empty ()
+		{
+			using var arr = MakeArray ();
+			Assert.That (arr.LastOrDefault (), Is.Null, "LastOrDefault empty");
+		}
+
+		[Test]
+		public void NSArray_LastOrDefault_Predicate_NoMatch ()
+		{
+			using var arr = MakeArray ("a", "b");
+			Assert.That (arr.LastOrDefault (s => s.ToString () == "z"), Is.Null, "LastOrDefault no match");
+		}
+
+		[Test]
+		public void NSArray_Single ()
+		{
+			using var arr = MakeArray ("only");
+			Assert.That (arr.Single ().ToString (), Is.EqualTo ("only"), "Single");
+		}
+
+		[Test]
+		public void NSArray_Single_Throws_OnEmpty ()
+		{
+			using var arr = MakeArray ();
+			Assert.Throws<InvalidOperationException> (() => arr.Single ());
+		}
+
+		[Test]
+		public void NSArray_Single_Throws_OnMultiple ()
+		{
+			using var arr = MakeArray ("a", "b");
+			Assert.Throws<InvalidOperationException> (() => arr.Single ());
+		}
+
+		[Test]
+		public void NSArray_SingleOrDefault_Empty ()
+		{
+			using var arr = MakeArray ();
+			Assert.That (arr.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
+		}
+
+		[Test]
+		public void NSArray_SingleOrDefault_Predicate ()
+		{
+			using var arr = MakeArray ("a", "b");
+			Assert.That (arr.SingleOrDefault (s => s.ToString () == "a")?.ToString (), Is.EqualTo ("a"), "SingleOrDefault predicate match");
+			Assert.That (arr.SingleOrDefault (s => s.ToString () == "z"), Is.Null, "SingleOrDefault predicate no match");
+		}
+
+		[Test]
+		public void NSArray_ElementAt ()
+		{
+			using var arr = MakeArray ("a", "b", "c");
+			Assert.That (arr.ElementAt (0).ToString (), Is.EqualTo ("a"), "ElementAt 0");
+			Assert.That (arr.ElementAt (2).ToString (), Is.EqualTo ("c"), "ElementAt 2");
+		}
+
+		[Test]
+		public void NSArray_ElementAt_OutOfRange_Throws ()
+		{
+			using var arr = MakeArray ("a");
+			Assert.Throws<ArgumentOutOfRangeException> (() => arr.ElementAt (5));
+		}
+
+		[Test]
+		public void NSArray_ElementAtOrDefault ()
+		{
+			using var arr = MakeArray ("a", "b");
+			Assert.That (arr.ElementAtOrDefault (1)?.ToString (), Is.EqualTo ("b"), "ElementAtOrDefault in range");
+			Assert.That (arr.ElementAtOrDefault (99), Is.Null, "ElementAtOrDefault out of range");
+		}
+
+		[Test]
+		public void NSArray_Any ()
+		{
+			using var empty = MakeArray ();
+			Assert.That (empty.Any (), Is.False, "Any empty");
+			using var arr = MakeArray ("a");
+			Assert.That (arr.Any (), Is.True, "Any non-empty");
+			Assert.That (arr.Any (s => s.ToString () == "a"), Is.True, "Any predicate true");
+			Assert.That (arr.Any (s => s.ToString () == "z"), Is.False, "Any predicate false");
+		}
+
+		[Test]
+		public void NSArray_All ()
+		{
+			using var arr = MakeArray ("ab", "abc");
+			Assert.That (arr.All (s => s.Length > 1), Is.True, "All true");
+			Assert.That (arr.All (s => s.Length > 2), Is.False, "All false");
+		}
+
+		[Test]
+		public void NSArray_Count ()
+		{
+			using var arr = MakeArray ("a", "b", "c");
+			Assert.That (arr.Count (), Is.EqualTo (3), "Count");
+			Assert.That (arr.Count (s => s.ToString () == "a"), Is.EqualTo (1), "Count predicate");
+		}
+
+		[Test]
+		public void NSArray_LongCount ()
+		{
+			using var arr = MakeArray ("a", "b");
+			Assert.That (arr.LongCount (), Is.EqualTo (2L), "LongCount");
+			Assert.That (arr.LongCount (s => s.ToString () == "a"), Is.EqualTo (1L), "LongCount predicate");
+		}
+
+		[Test]
+		public void NSArray_Where ()
+		{
+			using var arr = MakeArray ("a", "bb", "ccc");
+			var result = arr.Where (s => s.Length > 1).ToList ();
+			Assert.That (result.Count, Is.EqualTo (2), "Where count");
+		}
+
+		[Test]
+		public void NSArray_Where_Index ()
+		{
+			using var arr = MakeArray ("a", "b", "c");
+			var result = arr.Where ((s, i) => i % 2 == 0).ToList ();
+			Assert.That (result.Count, Is.EqualTo (2), "Where index count");
+			Assert.That (result [0].ToString (), Is.EqualTo ("a"), "Where index [0]");
+			Assert.That (result [1].ToString (), Is.EqualTo ("c"), "Where index [1]");
+		}
+
+		[Test]
+		public void NSArray_Select ()
+		{
+			using var arr = MakeArray ("hello", "world");
+			var lengths = arr.Select (s => s.Length).ToList ();
+			Assert.That (lengths [0], Is.EqualTo (5), "Select length [0]");
+			Assert.That (lengths [1], Is.EqualTo (5), "Select length [1]");
+		}
+
+		[Test]
+		public void NSArray_Select_Index ()
+		{
+			using var arr = MakeArray ("a", "b", "c");
+			var indexed = arr.Select ((s, i) => $"{i}:{s}").ToList ();
+			Assert.That (indexed [0], Is.EqualTo ("0:a"), "Select index 0");
+			Assert.That (indexed [2], Is.EqualTo ("2:c"), "Select index 2");
+		}
+
+		[Test]
+		public void NSArray_OrderBy ()
+		{
+			using var arr = MakeArray ("banana", "apple", "cherry");
+			var sorted = arr.OrderBy (s => s.ToString ()).ToList ();
+			Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
+			Assert.That (sorted [1].ToString (), Is.EqualTo ("banana"), "OrderBy second");
+			Assert.That (sorted [2].ToString (), Is.EqualTo ("cherry"), "OrderBy third");
+		}
+
+		[Test]
+		public void NSArray_OrderByDescending ()
+		{
+			using var arr = MakeArray ("banana", "apple", "cherry");
+			var sorted = arr.OrderByDescending (s => s.ToString ()).ToList ();
+			Assert.That (sorted [0].ToString (), Is.EqualTo ("cherry"), "OrderByDesc first");
+			Assert.That (sorted [2].ToString (), Is.EqualTo ("apple"), "OrderByDesc last");
+		}
+
+		[Test]
+		public void NSArray_Skip ()
+		{
+			using var arr = MakeArray ("a", "b", "c", "d");
+			var skipped = arr.Skip (2).ToList ();
+			Assert.That (skipped.Count, Is.EqualTo (2), "Skip count");
+			Assert.That (skipped [0].ToString (), Is.EqualTo ("c"), "Skip [0]");
+		}
+
+		[Test]
+		public void NSArray_SkipWhile ()
+		{
+			using var arr = MakeArray ("a", "b", "c");
+			var result = arr.SkipWhile (s => s.ToString () != "b").ToList ();
+			Assert.That (result.Count, Is.EqualTo (2), "SkipWhile count");
+			Assert.That (result [0].ToString (), Is.EqualTo ("b"), "SkipWhile first");
+		}
+
+		[Test]
+		public void NSArray_Take ()
+		{
+			using var arr = MakeArray ("a", "b", "c");
+			var taken = arr.Take (2).ToList ();
+			Assert.That (taken.Count, Is.EqualTo (2), "Take count");
+			Assert.That (taken [1].ToString (), Is.EqualTo ("b"), "Take [1]");
+		}
+
+		[Test]
+		public void NSArray_TakeWhile ()
+		{
+			using var arr = MakeArray ("a", "b", "c");
+			var taken = arr.TakeWhile (s => s.ToString () != "c").ToList ();
+			Assert.That (taken.Count, Is.EqualTo (2), "TakeWhile count");
+		}
+
+		[Test]
+		public void NSArray_Distinct ()
+		{
+			using var arr = MakeArray ("a", "a", "b");
+			var distinct = arr.Distinct ().ToList ();
+			Assert.That (distinct.Count, Is.EqualTo (2), "Distinct count");
+		}
+
+		[Test]
+		public void NSArray_Reverse ()
+		{
+			using var arr = MakeArray ("a", "b", "c");
+			var reversed = arr.Reverse ().ToList ();
+			Assert.That (reversed [0].ToString (), Is.EqualTo ("c"), "Reverse [0]");
+			Assert.That (reversed [2].ToString (), Is.EqualTo ("a"), "Reverse [2]");
+		}
+
+		[Test]
+		public void NSArray_Concat ()
+		{
+			using var arr = MakeArray ("a", "b");
+			var extra = new [] { S ("c") };
+			var all = arr.Concat (extra).ToList ();
+			Assert.That (all.Count, Is.EqualTo (3), "Concat count");
+			Assert.That (all [2].ToString (), Is.EqualTo ("c"), "Concat last");
+		}
+
+		[Test]
+		public void NSArray_ToList ()
+		{
+			using var arr = MakeArray ("a", "b", "c");
+			var list = arr.ToList ();
+			Assert.That (list, Is.TypeOf<List<NSString>> (), "ToList type");
+			Assert.That (list.Count, Is.EqualTo (3), "ToList count");
+		}
+
+		[Test]
+		public void NSArray_ToArray ()
+		{
+			using var arr = MakeArray ("a", "b");
+			var result = arr.ToArray ();
+			Assert.That (result, Is.TypeOf<NSString []> (), "ToArray type");
+			Assert.That (result.Length, Is.EqualTo (2), "ToArray length");
+		}
+
+		[Test]
+		public void NSArray_Aggregate ()
+		{
+			using var arr = MakeArray ("a", "b", "c");
+			var result = arr.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
+			Assert.That (result.ToString (), Is.EqualTo ("abc"), "Aggregate");
+		}
+
+		[Test]
+		public void NSArray_Aggregate_Seed ()
+		{
+			using var arr = MakeArray ("a", "b", "c");
+			var result = arr.Aggregate ("", (acc, s) => acc + s.ToString ());
+			Assert.That (result, Is.EqualTo ("abc"), "Aggregate seed");
+		}
+
+		// ===== NSMutableArray<T> =====
+
+		[Test]
+		public void NSMutableArray_First ()
+		{
+			using var arr = MakeMutableArray ("a", "b");
+			Assert.That (arr.First ().ToString (), Is.EqualTo ("a"), "First");
+		}
+
+		[Test]
+		public void NSMutableArray_First_Empty_Throws ()
+		{
+			using var arr = MakeMutableArray ();
+			Assert.Throws<InvalidOperationException> (() => arr.First ());
+		}
+
+		[Test]
+		public void NSMutableArray_FirstOrDefault_Empty ()
+		{
+			using var arr = MakeMutableArray ();
+			Assert.That (arr.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
+		}
+
+		[Test]
+		public void NSMutableArray_FirstOrDefault ()
+		{
+			using var arr = MakeMutableArray ("x", "y");
+			Assert.That (arr.FirstOrDefault ()?.ToString (), Is.EqualTo ("x"), "FirstOrDefault");
+		}
+
+		[Test]
+		public void NSMutableArray_Last ()
+		{
+			using var arr = MakeMutableArray ("a", "b", "c");
+			Assert.That (arr.Last ().ToString (), Is.EqualTo ("c"), "Last");
+		}
+
+		[Test]
+		public void NSMutableArray_LastOrDefault_Empty ()
+		{
+			using var arr = MakeMutableArray ();
+			Assert.That (arr.LastOrDefault (), Is.Null, "LastOrDefault empty");
+		}
+
+		[Test]
+		public void NSMutableArray_Single ()
+		{
+			using var arr = MakeMutableArray ("only");
+			Assert.That (arr.Single ().ToString (), Is.EqualTo ("only"), "Single");
+		}
+
+		[Test]
+		public void NSMutableArray_Single_Throws_OnMultiple ()
+		{
+			using var arr = MakeMutableArray ("a", "b");
+			Assert.Throws<InvalidOperationException> (() => arr.Single ());
+		}
+
+		[Test]
+		public void NSMutableArray_SingleOrDefault_Empty ()
+		{
+			using var arr = MakeMutableArray ();
+			Assert.That (arr.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
+		}
+
+		[Test]
+		public void NSMutableArray_ElementAt ()
+		{
+			using var arr = MakeMutableArray ("a", "b", "c");
+			Assert.That (arr.ElementAt (1).ToString (), Is.EqualTo ("b"), "ElementAt 1");
+		}
+
+		[Test]
+		public void NSMutableArray_ElementAtOrDefault ()
+		{
+			using var arr = MakeMutableArray ("a");
+			Assert.That (arr.ElementAtOrDefault (0)?.ToString (), Is.EqualTo ("a"), "ElementAtOrDefault in range");
+			Assert.That (arr.ElementAtOrDefault (10), Is.Null, "ElementAtOrDefault out of range");
+		}
+
+		[Test]
+		public void NSMutableArray_Any ()
+		{
+			using var empty = MakeMutableArray ();
+			Assert.That (empty.Any (), Is.False, "Any empty");
+			using var arr = MakeMutableArray ("a");
+			Assert.That (arr.Any (), Is.True, "Any non-empty");
+		}
+
+		[Test]
+		public void NSMutableArray_All ()
+		{
+			using var arr = MakeMutableArray ("ab", "abc");
+			Assert.That (arr.All (s => s.Length > 1), Is.True, "All true");
+		}
+
+		[Test]
+		public void NSMutableArray_Count ()
+		{
+			using var arr = MakeMutableArray ("a", "b", "c");
+			Assert.That (arr.Count (), Is.EqualTo (3), "Count");
+		}
+
+		[Test]
+		public void NSMutableArray_LongCount ()
+		{
+			using var arr = MakeMutableArray ("a", "b");
+			Assert.That (arr.LongCount (), Is.EqualTo (2L), "LongCount");
+		}
+
+		[Test]
+		public void NSMutableArray_Where ()
+		{
+			using var arr = MakeMutableArray ("a", "bb", "ccc");
+			var result = arr.Where (s => s.Length > 1).ToList ();
+			Assert.That (result.Count, Is.EqualTo (2), "Where count");
+		}
+
+		[Test]
+		public void NSMutableArray_Select ()
+		{
+			using var arr = MakeMutableArray ("hello", "world");
+			var lengths = arr.Select (s => s.Length).ToList ();
+			Assert.That (lengths [0], Is.EqualTo (5), "Select [0]");
+		}
+
+		[Test]
+		public void NSMutableArray_OrderBy ()
+		{
+			using var arr = MakeMutableArray ("banana", "apple", "cherry");
+			var sorted = arr.OrderBy (s => s.ToString ()).ToList ();
+			Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
+		}
+
+		[Test]
+		public void NSMutableArray_OrderByDescending ()
+		{
+			using var arr = MakeMutableArray ("banana", "apple", "cherry");
+			var sorted = arr.OrderByDescending (s => s.ToString ()).ToList ();
+			Assert.That (sorted [0].ToString (), Is.EqualTo ("cherry"), "OrderByDesc first");
+		}
+
+		[Test]
+		public void NSMutableArray_Skip_Take ()
+		{
+			using var arr = MakeMutableArray ("a", "b", "c", "d");
+			var sliced = arr.Skip (1).Take (2).ToList ();
+			Assert.That (sliced.Count, Is.EqualTo (2), "Skip/Take count");
+		}
+
+		[Test]
+		public void NSMutableArray_SkipWhile_TakeWhile ()
+		{
+			using var arr = MakeMutableArray ("a", "b", "c");
+			var skipped = arr.SkipWhile (s => s.ToString () == "a").ToList ();
+			Assert.That (skipped.Count, Is.EqualTo (2), "SkipWhile count");
+			var taken = arr.TakeWhile (s => s.ToString () != "c").ToList ();
+			Assert.That (taken.Count, Is.EqualTo (2), "TakeWhile count");
+		}
+
+		[Test]
+		public void NSMutableArray_Distinct ()
+		{
+			using var arr = MakeMutableArray ("a", "a", "b");
+			var distinct = arr.Distinct ().ToList ();
+			Assert.That (distinct.Count, Is.EqualTo (2), "Distinct count");
+		}
+
+		[Test]
+		public void NSMutableArray_Reverse ()
+		{
+			using var arr = MakeMutableArray ("a", "b", "c");
+			var reversed = arr.Reverse ().ToList ();
+			Assert.That (reversed [0].ToString (), Is.EqualTo ("c"), "Reverse [0]");
+		}
+
+		[Test]
+		public void NSMutableArray_Concat ()
+		{
+			using var arr = MakeMutableArray ("a");
+			var all = arr.Concat (new [] { S ("b") }).ToList ();
+			Assert.That (all.Count, Is.EqualTo (2), "Concat count");
+		}
+
+		[Test]
+		public void NSMutableArray_ToList ()
+		{
+			using var arr = MakeMutableArray ("a", "b");
+			var list = arr.ToList ();
+			Assert.That (list.Count, Is.EqualTo (2), "ToList count");
+		}
+
+		[Test]
+		public void NSMutableArray_ToArray ()
+		{
+			using var arr = MakeMutableArray ("a", "b");
+			var result = arr.ToArray ();
+			Assert.That (result.Length, Is.EqualTo (2), "ToArray length");
+		}
+
+		[Test]
+		public void NSMutableArray_Aggregate ()
+		{
+			using var arr = MakeMutableArray ("a", "b", "c");
+			var result = arr.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
+			Assert.That (result.ToString (), Is.EqualTo ("abc"), "Aggregate");
+		}
+
+		[Test]
+		public void NSMutableArray_Aggregate_Seed ()
+		{
+			using var arr = MakeMutableArray ("a", "b", "c");
+			var result = arr.Aggregate (0, (acc, s) => acc + s.Length);
+			Assert.That (result, Is.EqualTo (3), "Aggregate seed");
+		}
+
+		// ===== NSOrderedSet<T> =====
+
+		[Test]
+		public void NSOrderedSet_First ()
+		{
+			using var set = MakeOrderedSet ("a", "b", "c");
+			Assert.That (set.First ().ToString (), Is.EqualTo ("a"), "First");
+		}
+
+		[Test]
+		public void NSOrderedSet_First_Predicate ()
+		{
+			using var set = MakeOrderedSet ("a", "b", "c");
+			Assert.That (set.First (s => s.ToString () == "c").ToString (), Is.EqualTo ("c"), "First predicate");
+		}
+
+		[Test]
+		public void NSOrderedSet_First_Empty_Throws ()
+		{
+			using var set = MakeOrderedSet ();
+			Assert.Throws<InvalidOperationException> (() => set.First ());
+		}
+
+		[Test]
+		public void NSOrderedSet_FirstOrDefault_Empty ()
+		{
+			using var set = MakeOrderedSet ();
+			Assert.That (set.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
+		}
+
+		[Test]
+		public void NSOrderedSet_FirstOrDefault ()
+		{
+			using var set = MakeOrderedSet ("x", "y");
+			Assert.That (set.FirstOrDefault ()?.ToString (), Is.EqualTo ("x"), "FirstOrDefault");
+		}
+
+		[Test]
+		public void NSOrderedSet_Last ()
+		{
+			using var set = MakeOrderedSet ("a", "b", "c");
+			Assert.That (set.Last ().ToString (), Is.EqualTo ("c"), "Last");
+		}
+
+		[Test]
+		public void NSOrderedSet_Last_Predicate ()
+		{
+			using var set = MakeOrderedSet ("a", "b", "c");
+			Assert.That (set.Last (s => s.ToString () != "c").ToString (), Is.EqualTo ("b"), "Last predicate");
+		}
+
+		[Test]
+		public void NSOrderedSet_Last_Empty_Throws ()
+		{
+			using var set = MakeOrderedSet ();
+			Assert.Throws<InvalidOperationException> (() => set.Last ());
+		}
+
+		[Test]
+		public void NSOrderedSet_LastOrDefault_Empty ()
+		{
+			using var set = MakeOrderedSet ();
+			Assert.That (set.LastOrDefault (), Is.Null, "LastOrDefault empty");
+		}
+
+		[Test]
+		public void NSOrderedSet_Single ()
+		{
+			using var set = MakeOrderedSet ("only");
+			Assert.That (set.Single ().ToString (), Is.EqualTo ("only"), "Single");
+		}
+
+		[Test]
+		public void NSOrderedSet_Single_Throws_OnMultiple ()
+		{
+			using var set = MakeOrderedSet ("a", "b");
+			Assert.Throws<InvalidOperationException> (() => set.Single ());
+		}
+
+		[Test]
+		public void NSOrderedSet_SingleOrDefault_Empty ()
+		{
+			using var set = MakeOrderedSet ();
+			Assert.That (set.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
+		}
+
+		[Test]
+		public void NSOrderedSet_SingleOrDefault_Predicate ()
+		{
+			using var set = MakeOrderedSet ("a", "b");
+			Assert.That (set.SingleOrDefault (s => s.ToString () == "a")?.ToString (), Is.EqualTo ("a"), "SingleOrDefault predicate match");
+		}
+
+		[Test]
+		public void NSOrderedSet_ElementAt ()
+		{
+			using var set = MakeOrderedSet ("a", "b", "c");
+			Assert.That (set.ElementAt (1).ToString (), Is.EqualTo ("b"), "ElementAt 1");
+		}
+
+		[Test]
+		public void NSOrderedSet_ElementAtOrDefault ()
+		{
+			using var set = MakeOrderedSet ("a");
+			Assert.That (set.ElementAtOrDefault (0)?.ToString (), Is.EqualTo ("a"), "in range");
+			Assert.That (set.ElementAtOrDefault (5), Is.Null, "out of range");
+		}
+
+		[Test]
+		public void NSOrderedSet_Any ()
+		{
+			using var empty = MakeOrderedSet ();
+			Assert.That (empty.Any (), Is.False, "Any empty");
+			using var set = MakeOrderedSet ("a");
+			Assert.That (set.Any (), Is.True, "Any non-empty");
+			Assert.That (set.Any (s => s.ToString () == "a"), Is.True, "Any predicate true");
+			Assert.That (set.Any (s => s.ToString () == "z"), Is.False, "Any predicate false");
+		}
+
+		[Test]
+		public void NSOrderedSet_All ()
+		{
+			using var set = MakeOrderedSet ("ab", "abc");
+			Assert.That (set.All (s => s.Length > 1), Is.True, "All true");
+			Assert.That (set.All (s => s.Length > 2), Is.False, "All false");
+		}
+
+		[Test]
+		public void NSOrderedSet_Count ()
+		{
+			using var set = MakeOrderedSet ("a", "b", "c");
+			Assert.That (set.Count (), Is.EqualTo (3), "Count");
+			Assert.That (set.Count (s => s.ToString () == "a"), Is.EqualTo (1), "Count predicate");
+		}
+
+		[Test]
+		public void NSOrderedSet_LongCount ()
+		{
+			using var set = MakeOrderedSet ("a", "b");
+			Assert.That (set.LongCount (), Is.EqualTo (2L), "LongCount");
+		}
+
+		[Test]
+		public void NSOrderedSet_Where ()
+		{
+			using var set = MakeOrderedSet ("a", "bb", "ccc");
+			var result = set.Where (s => s.Length > 1).ToList ();
+			Assert.That (result.Count, Is.EqualTo (2), "Where count");
+		}
+
+		[Test]
+		public void NSOrderedSet_Where_Index ()
+		{
+			using var set = MakeOrderedSet ("a", "b", "c");
+			var result = set.Where ((s, i) => i % 2 == 0).ToList ();
+			Assert.That (result.Count, Is.EqualTo (2), "Where index count");
+		}
+
+		[Test]
+		public void NSOrderedSet_Select ()
+		{
+			using var set = MakeOrderedSet ("hello", "world");
+			var lengths = set.Select (s => s.Length).ToList ();
+			Assert.That (lengths [0], Is.EqualTo (5), "Select [0]");
+		}
+
+		[Test]
+		public void NSOrderedSet_Select_Index ()
+		{
+			using var set = MakeOrderedSet ("a", "b");
+			var indexed = set.Select ((s, i) => $"{i}:{s}").ToList ();
+			Assert.That (indexed [0], Is.EqualTo ("0:a"), "Select index 0");
+		}
+
+		[Test]
+		public void NSOrderedSet_OrderBy ()
+		{
+			using var set = MakeOrderedSet ("banana", "apple", "cherry");
+			var sorted = set.OrderBy (s => s.ToString ()).ToList ();
+			Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
+		}
+
+		[Test]
+		public void NSOrderedSet_OrderByDescending ()
+		{
+			using var set = MakeOrderedSet ("banana", "apple", "cherry");
+			var sorted = set.OrderByDescending (s => s.ToString ()).ToList ();
+			Assert.That (sorted [0].ToString (), Is.EqualTo ("cherry"), "OrderByDesc first");
+		}
+
+		[Test]
+		public void NSOrderedSet_Skip_Take ()
+		{
+			using var set = MakeOrderedSet ("a", "b", "c", "d");
+			var sliced = set.Skip (1).Take (2).ToList ();
+			Assert.That (sliced.Count, Is.EqualTo (2), "Skip/Take count");
+			Assert.That (sliced [0].ToString (), Is.EqualTo ("b"), "Skip/Take [0]");
+		}
+
+		[Test]
+		public void NSOrderedSet_SkipWhile_TakeWhile ()
+		{
+			using var set = MakeOrderedSet ("a", "b", "c");
+			var skipped = set.SkipWhile (s => s.ToString () == "a").ToList ();
+			Assert.That (skipped.Count, Is.EqualTo (2), "SkipWhile count");
+			var taken = set.TakeWhile (s => s.ToString () != "c").ToList ();
+			Assert.That (taken.Count, Is.EqualTo (2), "TakeWhile count");
+		}
+
+		[Test]
+		public void NSOrderedSet_Distinct ()
+		{
+			using var set = MakeOrderedSet ("a", "b");
+			var distinct = set.Distinct ().ToList ();
+			Assert.That (distinct.Count, Is.EqualTo (2), "Distinct count");
+		}
+
+		[Test]
+		public void NSOrderedSet_Reverse ()
+		{
+			using var set = MakeOrderedSet ("a", "b", "c");
+			var reversed = set.Reverse ().ToList ();
+			Assert.That (reversed [0].ToString (), Is.EqualTo ("c"), "Reverse [0]");
+			Assert.That (reversed [2].ToString (), Is.EqualTo ("a"), "Reverse [2]");
+		}
+
+		[Test]
+		public void NSOrderedSet_Concat ()
+		{
+			using var set = MakeOrderedSet ("a", "b");
+			var all = set.Concat (new [] { S ("c") }).ToList ();
+			Assert.That (all.Count, Is.EqualTo (3), "Concat count");
+		}
+
+		[Test]
+		public void NSOrderedSet_ToList ()
+		{
+			using var set = MakeOrderedSet ("a", "b");
+			var list = set.ToList ();
+			Assert.That (list.Count, Is.EqualTo (2), "ToList count");
+		}
+
+		[Test]
+		public void NSOrderedSet_ToArray ()
+		{
+			using var set = MakeOrderedSet ("a", "b");
+			var arr = set.ToArray ();
+			Assert.That (arr.Length, Is.EqualTo (2), "ToArray length");
+		}
+
+		[Test]
+		public void NSOrderedSet_Aggregate ()
+		{
+			using var set = MakeOrderedSet ("a", "b", "c");
+			var result = set.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
+			Assert.That (result.ToString (), Is.EqualTo ("abc"), "Aggregate");
+		}
+
+		[Test]
+		public void NSOrderedSet_Aggregate_Seed ()
+		{
+			using var set = MakeOrderedSet ("a", "b", "c");
+			var result = set.Aggregate ("", (acc, s) => acc + s.ToString ());
+			Assert.That (result, Is.EqualTo ("abc"), "Aggregate seed");
+		}
+
+		// ===== NSMutableOrderedSet<T> =====
+
+		[Test]
+		public void NSMutableOrderedSet_First ()
+		{
+			using var set = MakeMutableOrderedSet ("a", "b", "c");
+			Assert.That (set.First ().ToString (), Is.EqualTo ("a"), "First");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_First_Empty_Throws ()
+		{
+			using var set = MakeMutableOrderedSet ();
+			Assert.Throws<InvalidOperationException> (() => set.First ());
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_FirstOrDefault_Empty ()
+		{
+			using var set = MakeMutableOrderedSet ();
+			Assert.That (set.FirstOrDefault (), Is.Null, "FirstOrDefault empty");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_FirstOrDefault ()
+		{
+			using var set = MakeMutableOrderedSet ("x", "y");
+			Assert.That (set.FirstOrDefault ()?.ToString (), Is.EqualTo ("x"), "FirstOrDefault");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_FirstOrDefault_Predicate ()
+		{
+			using var set = MakeMutableOrderedSet ("a", "b", "c");
+			Assert.That (set.FirstOrDefault (s => s.ToString () == "b")?.ToString (), Is.EqualTo ("b"), "FirstOrDefault predicate match");
+			Assert.That (set.FirstOrDefault (s => s.ToString () == "z"), Is.Null, "FirstOrDefault predicate no match");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_Last ()
+		{
+			using var set = MakeMutableOrderedSet ("a", "b", "c");
+			Assert.That (set.Last ().ToString (), Is.EqualTo ("c"), "Last");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_LastOrDefault_Empty ()
+		{
+			using var set = MakeMutableOrderedSet ();
+			Assert.That (set.LastOrDefault (), Is.Null, "LastOrDefault empty");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_Single ()
+		{
+			using var set = MakeMutableOrderedSet ("only");
+			Assert.That (set.Single ().ToString (), Is.EqualTo ("only"), "Single");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_Single_Throws_OnMultiple ()
+		{
+			using var set = MakeMutableOrderedSet ("a", "b");
+			Assert.Throws<InvalidOperationException> (() => set.Single ());
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_SingleOrDefault_Empty ()
+		{
+			using var set = MakeMutableOrderedSet ();
+			Assert.That (set.SingleOrDefault (), Is.Null, "SingleOrDefault empty");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_ElementAt ()
+		{
+			using var set = MakeMutableOrderedSet ("a", "b", "c");
+			Assert.That (set.ElementAt (2).ToString (), Is.EqualTo ("c"), "ElementAt 2");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_ElementAtOrDefault ()
+		{
+			using var set = MakeMutableOrderedSet ("a");
+			Assert.That (set.ElementAtOrDefault (0)?.ToString (), Is.EqualTo ("a"), "in range");
+			Assert.That (set.ElementAtOrDefault (5), Is.Null, "out of range");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_Any ()
+		{
+			using var empty = MakeMutableOrderedSet ();
+			Assert.That (empty.Any (), Is.False, "Any empty");
+			using var set = MakeMutableOrderedSet ("a");
+			Assert.That (set.Any (), Is.True, "Any non-empty");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_All ()
+		{
+			using var set = MakeMutableOrderedSet ("ab", "abc");
+			Assert.That (set.All (s => s.Length > 1), Is.True, "All true");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_Count ()
+		{
+			using var set = MakeMutableOrderedSet ("a", "b", "c");
+			Assert.That (set.Count (), Is.EqualTo (3), "Count");
+			Assert.That (set.Count (s => s.ToString () == "a"), Is.EqualTo (1), "Count predicate");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_LongCount ()
+		{
+			using var set = MakeMutableOrderedSet ("a", "b");
+			Assert.That (set.LongCount (), Is.EqualTo (2L), "LongCount");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_Where ()
+		{
+			using var set = MakeMutableOrderedSet ("a", "bb", "ccc");
+			var result = set.Where (s => s.Length > 1).ToList ();
+			Assert.That (result.Count, Is.EqualTo (2), "Where count");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_Select ()
+		{
+			using var set = MakeMutableOrderedSet ("hello", "world");
+			var lengths = set.Select (s => s.Length).ToList ();
+			Assert.That (lengths [0], Is.EqualTo (5), "Select [0]");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_OrderBy ()
+		{
+			using var set = MakeMutableOrderedSet ("banana", "apple", "cherry");
+			var sorted = set.OrderBy (s => s.ToString ()).ToList ();
+			Assert.That (sorted [0].ToString (), Is.EqualTo ("apple"), "OrderBy first");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_OrderByDescending ()
+		{
+			using var set = MakeMutableOrderedSet ("banana", "apple", "cherry");
+			var sorted = set.OrderByDescending (s => s.ToString ()).ToList ();
+			Assert.That (sorted [0].ToString (), Is.EqualTo ("cherry"), "OrderByDesc first");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_Skip_Take ()
+		{
+			using var set = MakeMutableOrderedSet ("a", "b", "c", "d");
+			var sliced = set.Skip (1).Take (2).ToList ();
+			Assert.That (sliced.Count, Is.EqualTo (2), "Skip/Take count");
+			Assert.That (sliced [0].ToString (), Is.EqualTo ("b"), "Skip/Take [0]");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_SkipWhile_TakeWhile ()
+		{
+			using var set = MakeMutableOrderedSet ("a", "b", "c");
+			var skipped = set.SkipWhile (s => s.ToString () == "a").ToList ();
+			Assert.That (skipped.Count, Is.EqualTo (2), "SkipWhile count");
+			var taken = set.TakeWhile (s => s.ToString () != "c").ToList ();
+			Assert.That (taken.Count, Is.EqualTo (2), "TakeWhile count");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_Distinct ()
+		{
+			using var set = MakeMutableOrderedSet ("a", "b");
+			var distinct = set.Distinct ().ToList ();
+			Assert.That (distinct.Count, Is.EqualTo (2), "Distinct count");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_Reverse ()
+		{
+			using var set = MakeMutableOrderedSet ("a", "b", "c");
+			var reversed = set.Reverse ().ToList ();
+			Assert.That (reversed [0].ToString (), Is.EqualTo ("c"), "Reverse [0]");
+			Assert.That (reversed [2].ToString (), Is.EqualTo ("a"), "Reverse [2]");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_Concat ()
+		{
+			using var set = MakeMutableOrderedSet ("a", "b");
+			var all = set.Concat (new [] { S ("c") }).ToList ();
+			Assert.That (all.Count, Is.EqualTo (3), "Concat count");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_ToList ()
+		{
+			using var set = MakeMutableOrderedSet ("a", "b");
+			var list = set.ToList ();
+			Assert.That (list.Count, Is.EqualTo (2), "ToList count");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_ToArray ()
+		{
+			using var set = MakeMutableOrderedSet ("a", "b");
+			var arr = set.ToArray ();
+			Assert.That (arr.Length, Is.EqualTo (2), "ToArray length");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_Aggregate ()
+		{
+			using var set = MakeMutableOrderedSet ("a", "b", "c");
+			var result = set.Aggregate ((acc, s) => (NSString) (acc.ToString () + s.ToString ()));
+			Assert.That (result.ToString (), Is.EqualTo ("abc"), "Aggregate");
+		}
+
+		[Test]
+		public void NSMutableOrderedSet_Aggregate_Seed ()
+		{
+			using var set = MakeMutableOrderedSet ("a", "b", "c");
+			var result = set.Aggregate ("", (acc, s) => acc + s.ToString ());
+			Assert.That (result, Is.EqualTo ("abc"), "Aggregate seed");
+		}
+	}
 }