Broke the autorelease code out into a class and replaced the usage.

src/OpenTK/OpenTK.csproj

@@ -137,6 +137,7 @@
     <Compile Include="Platform\Egl\EglUnixContext.cs" />
     <Compile Include="Platform\Egl\EglWinContext.cs" />
     <Compile Include="Platform\Egl\EglAnglePlatformFactory.cs" />
+    <Compile Include="Platform\MacOS\Cocoa\NSAutoreleasePool.cs" />
     <Compile Include="Platform\MappedGamePadDriver.cs" />
     <Compile Include="Platform\Windows\Bindings\HidProtocol.cs" />
     <Compile Include="Platform\Windows\WinInputBase.cs" />

src/OpenTK/Platform/MacOS/Cocoa/NSAutoreleasePool.cs

@@ -0,0 +1,34 @@
+using System;
+
+namespace OpenTK.Platform.MacOS
+{
+    /// <summary>
+    /// The <see cref="NSAutoreleasePool"/> class is a wrapper around the native objective-C NSAutoreleasePool.
+    /// In particular, this construct mimics the usage of an @autorelease block and can be used in much the same way,
+    /// only with a C# using block instead.
+    /// </summary>
+    public sealed class NSAutoreleasePool : IDisposable
+    {
+        private readonly IntPtr _autoreleasePool;
+
+        /// <summary>
+        /// Allocates and initializes a new <see cref="NSAutoreleasePool"/>.
+        /// </summary>
+        public NSAutoreleasePool()
+        {
+            _autoreleasePool = Cocoa.SendIntPtr(Class.NSAutoreleasePool, Selector.Get("alloc"));
+            _autoreleasePool = Cocoa.SendIntPtr(_autoreleasePool, Selector.Get("init"));
+        }
+
+        /// <summary>
+        /// Disposes of the <see cref="NSAutoreleasePool"/> instance, draining it.
+        /// </summary>
+        public void Dispose()
+        {
+            if (_autoreleasePool != IntPtr.Zero)
+            {
+                Cocoa.SendVoid(_autoreleasePool, Selector.Get("drain"));
+            }
+        }
+    }
+}

src/OpenTK/Platform/MacOS/CocoaContext.cs

@@ -54,8 +54,6 @@ namespace OpenTK
             "/System/Library/Frameworks/OpenGL.framework/OpenGLES",
             AddImageFlags.ReturnOnError);
 
-        private IntPtr autoreleasePool;
-
         static CocoaContext()
         {
             Cocoa.Initialize();
@@ -119,10 +117,6 @@ namespace OpenTK
 
         private void CreateContext(GraphicsMode mode, CocoaWindowInfo cocoaWindow, IntPtr shareContextRef, int majorVersion, int minorVersion, bool fullscreen)
         {
-            // Create a new autorelease pool for allocations in this context (mach ports, etc)
-            autoreleasePool = Cocoa.SendIntPtr(Class.NSAutoreleasePool, Selector.Get("alloc"));
-            autoreleasePool = Cocoa.SendIntPtr(autoreleasePool, Selector.Get("init"));
-
             // Prepare attributes
             IntPtr pixelFormat = SelectPixelFormat(mode, majorVersion, minorVersion);
             if (pixelFormat == IntPtr.Zero)
@@ -346,22 +340,16 @@ namespace OpenTK
 
             Debug.Print("Disposing of Cocoa context.");
 
-            if (!NSApplication.IsUIThread)
+            using (var pool = new NSAutoreleasePool())
-            {
+            {if (!NSApplication.IsUIThread)
-                return;
+            {    return;}
-            }
 
             if (IsCurrent)
-            {
+            {    Cocoa.SendVoid(NSOpenGLContext, Selector.Get("clearCurrentContext"));}
-                Cocoa.SendVoid(NSOpenGLContext, Selector.Get("clearCurrentContext"));
-            }
             Cocoa.SendVoid(Handle.Handle, Selector.Get("clearDrawable"));
             Cocoa.SendVoid(Handle.Handle, Selector.Get("release"));
 
-            // Drain the autorelease pool for the context, closing mach ports (if there is one)
+
-            if (autoreleasePool != IntPtr.Zero)
-            {
-                Cocoa.SendVoid(autoreleasePool, Selector.Get("drain"));
             }
 
             Handle = ContextHandle.Zero;