AppDelegate.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using MonoTouch.Foundation;
using MonoTouch.UIKit;

namespace perf1
{
    [Register("AppDelegate")]
 public partial class AppDelegate : UIApplicationDelegate
	{
		UIWindow window;
		UINavigationController navController;

		public override bool FinishedLaunching (UIApplication app, NSDictionary options)
		{
			window = new UIWindow (UIScreen.MainScreen.Bounds);

			navController = new UINavigationController ();

			window.Frame = UIScreen.MainScreen.Bounds;
			window.RootViewController = navController;
			window.MakeKeyAndVisible ();

			UIViewController root = new UIViewController ();
			root.View.AddSubview (new UIView (){BackgroundColor=UIColor.Green, Frame=root.View.Bounds});
			navController.PushViewController (root, false);
			root = null;

			PushPopViewController ("one", false, true); // MyView & MyViewController instances should get garbage collected afterwards, and will be
			PushPopViewController ("two", true, true); // MyView & MyViewController instances should get garbage collected afterwards, and will not be

			GC.Collect ();
			Console.WriteLine ("GC");

			PushPopViewController ("three", false, false); // MyView & MyViewController instances should get garbage collected after navigating back, and will not be
			PushPopViewController ("four", true, false); // MyView & MyViewController instances should get garbage collected after navigating back, and will not be
			
			//FixCase3 ();
			
			return true;
		}

		void FixCase3 ()
		{
			// This fixes case 3: 
			ThreadPool.QueueUserWorkItem ((v) =>
			{
				while (true) {
					Thread.Sleep (1000);
					InvokeOnMainThread (() =>
					{
						Console.WriteLine ("ViewControllers: {0}", navController.ViewControllers.Length);
					});
				}
			});
		}
		
		void PushPopViewController (string name, bool referenceViewController, bool pop)
		{
			MyViewController myViewController = new MyViewController (name);
			navController.PushViewController (myViewController, false);
			UIView view1 = myViewController.View; // cause the view to get instantiated, even if doesn't get displayed
			if (pop)
				navController.PopViewControllerAnimated (false);
		}

		class MyView : UIView
		{
			string name;

			public MyView (string name)
			{
				this.name = name;
				Console.WriteLine ("MyView() " + name);
				BackgroundColor = UIColor.Yellow;
			}

			~MyView ()
			{
				Console.WriteLine ("~MyView() " + name);
			}
		}

		class MyViewController : UIViewController
		{
			string name;

			public override void LoadView ()
			{
				View = new MyView (name);
			}

			public MyViewController (string name)
			{
				this.name = name;
				Console.WriteLine ("MyViewController() " + name);
			}

			~MyViewController ()
			{
				Console.WriteLine ("~MyViewController() " + name);
			}
		}
	}
}