[MonoTouch] SDK 5 issue

[Sergio Fadda]

Ok, after solving the issue in the topic, I finally isolated the problem I
have in my project.
Should be a synchronization issue with the GC.
Here's the app that replicate the issue:


using System;
using System.Drawing;
using MonoTouch.Foundation;
using MonoTouch.UIKit;

namespace MTFailure
{
	public class Application
	{
		static void Main (string[] args)
		{
			UIApplication.Main (args, null, "AppDelegate");
		}
	}
	
	public class MyUIOperation : NSOperation
	{
		private NSAction _action;
		
		public MyUIOperation(NSAction action)
		{
			_action = action;
		}
		
		public override void Main ()
		{
			// Execute these actions in the main thread since it's a UI manipulation
			InvokeOnMainThread(_action);
		}
	}
	
	[Register("AppDelegate")]
	public class AppDelegate : UIApplicationDelegate
	{
		private MonoTouch.UIKit.UIWindow __mt_window;
		private UINavigationController _navCtrl;
		
		public override bool FinishedLaunching (UIApplication app, NSDictionary
options)
		{
			__mt_window = new UIWindow(UIScreen.MainScreen.Bounds);
			__mt_window.BackgroundColor = UIColor.White;
			
			_navCtrl = new UINavigationController();
			_navCtrl.PushViewController(CreatePage(), true);
			
			__mt_window.AddSubview(_navCtrl.View);
			__mt_window.MakeKeyAndVisible ();
	
			return true;
		}
		
		protected UIViewController CreatePage()
		{
			UIViewController result = new UIViewController();
			UIView pageView = new UIView(UIScreen.MainScreen.Bounds);
			
			UIButton btn = UIButton.FromType(UIButtonType.RoundedRect);
			btn.Frame = new RectangleF(0, 50, 320, 37);
			btn.TouchUpInside += HandleBtnTouchUpInside;
			btn.SetTitle("Touch me!!!", UIControlState.Normal);
			pageView.AddSubview(btn);
			
			result.View = pageView;
			
			return result;
		}

		private NSOperationQueue _queue = new NSOperationQueue();
		private NSOperation _op;
		
		void HandleBtnTouchUpInside (object sender, EventArgs e)
		{
			// Enqueue the operation and let the os to handle it in another thread
			_op = new MyUIOperation(DeferredAction);
			_queue.AddOperation(_op);
		}
		
		private UIViewController _subCtrl;
		
		private void DeferredAction()
		{
			_navCtrl.PushViewController(CreatePage (), true);
		}

		// This method is required in iPhoneOS 3.0
		public override void OnActivated (UIApplication application)
		{
		}
	}
}


That is, a simple navigation app with a button in a view; the action of the
button must be deferred and usually is a UI manipulation; running the
application and pressing the button a variable number of times the
application crashes and displays the following message:


Stacktrace:


Native stacktrace:

	0   MTFailure                           0x000d5c18
mono_handle_native_sigsegv + 408
	1   MTFailure                           0x00012fcf
mono_sigsegv_signal_handler + 351
	2   libsystem_c.dylib                   0x9435859b _sigtramp + 43
	3   ???                                 0xffffffff 0x0 + 4294967295
	4   libobjc.A.dylib                     0x0199dc09 _class_getVariable + 99
	5   libobjc.A.dylib                     0x0199415f
object_getInstanceVariable + 56
	6   MTFailure                           0x002cc543
monotouch_release_trampoline + 419
	7   Foundation                          0x00747d16 __release_object_op + 37
	8   libdispatch.dylib                   0x0214cc7b
_dispatch_async_f_redirect_invoke + 146
	9   libdispatch.dylib                   0x0214c4e6 _dispatch_worker_thread2
+ 284
	10  libsystem_c.dylib                   0x94302b24 _pthread_wqthread + 346
	11  libsystem_c.dylib                   0x943046fe start_wqthread + 30

=================================================================
Got a SIGSEGV while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries 
used by your application.
=================================================================

This issue is present only with iOS 5 (both device and simulator), but in
iOS 4.3 works fine!
What's wrong now?


Thanks,

Sergio

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