macOS native: fix destructors accessing freed .NET objects

native/Avalonia.Native/src/OSX/app.mm

@@ -2,6 +2,7 @@
 #include "AvnString.h"
 @interface AvnAppDelegate : NSObject<NSApplicationDelegate>
 -(AvnAppDelegate* _Nonnull) initWithEvents: (IAvnApplicationEvents* _Nonnull) events;
+-(void) releaseEvents;
 @end
 
 NSApplicationActivationPolicy AvnDesiredActivationPolicy = NSApplicationActivationPolicyRegular;
@@ -15,6 +16,11 @@ ComPtr<IAvnApplicationEvents> _events;
     return self;
 }
 
+- (void)releaseEvents
+{
+    _events = nil;
+}
+
 - (void)applicationWillFinishLaunching:(NSNotification *)notification
 {
     if([[NSApplication sharedApplication] activationPolicy] != AvnDesiredActivationPolicy)
@@ -105,6 +111,18 @@ extern void InitializeAvnApp(IAvnApplicationEvents* events, bool disableAppDeleg
     }
 }
 
+extern void ReleaseAvnAppEvents()
+{
+    NSApplication* app = [AvnApplication sharedApplication];
+    id delegate = [app delegate];
+    if ([delegate isMemberOfClass:[AvnAppDelegate class]])
+    {
+        AvnAppDelegate* avnDelegate = delegate;
+        [avnDelegate releaseEvents];
+        [app setDelegate:nil];
+    }
+}
+
 HRESULT AvnApplicationCommands::HideApp()
 {
     START_COM_CALL;

native/Avalonia.Native/src/OSX/common.h

@@ -38,6 +38,7 @@ extern IAvnMenu* GetAppMenu ();
 extern NSMenuItem* GetAppMenuItem ();
 
 extern void InitializeAvnApp(IAvnApplicationEvents* events, bool disableAppDelegate);
+extern void ReleaseAvnAppEvents();
 extern NSApplicationActivationPolicy AvnDesiredActivationPolicy;
 extern NSPoint ToNSPoint (AvnPoint p);
 extern NSRect ToNSRect (AvnRect r);

native/Avalonia.Native/src/OSX/main.mm

@@ -197,6 +197,13 @@ class AvaloniaNative : public ComSingleObject<IAvaloniaNativeFactory, &IID_IAval
     
 public:
     FORWARD_IUNKNOWN()
+    
+    virtual ~AvaloniaNative() override {
+        ReleaseAvnAppEvents();
+        _deallocator = nullptr;
+        _dispatcher = nullptr;
+    }
+    
     virtual HRESULT Initialize(IAvnGCHandleDeallocatorCallback* deallocator,
             IAvnApplicationEvents* events,
             IAvnDispatcher* dispatcher) override

src/Avalonia.Native/AvaloniaNativePlatform.cs

@@ -3,9 +3,7 @@ using System.Runtime.InteropServices;
 using Avalonia.Controls.Platform;
 using Avalonia.Input;
 using Avalonia.Input.Platform;
-using Avalonia.MicroCom;
 using Avalonia.Native.Interop;
-using Avalonia.OpenGL;
 using Avalonia.Platform;
 using Avalonia.Rendering;
 using Avalonia.Rendering.Composition;
@@ -163,6 +161,14 @@ namespace Avalonia.Native
             
 
             Compositor = new Compositor(_platformGraphics, true);
+
+            Dispatcher.UIThread.ShutdownFinished += OnDispatcherShutdownFinished;
+        }
+
+        private void OnDispatcherShutdownFinished(object? sender, EventArgs e)
+        {
+            Dispatcher.UIThread.ShutdownFinished -= OnDispatcherShutdownFinished;
+            _factory.Dispose();
         }
 
         public ITrayIconImpl CreateTrayIcon()