gistfile1.txt

using System;
using MonoTouch.UIKit;
using System.Linq;

namespace Xamarin.iOS.UIPageViewControllerMemory
{
    public class StartDialog : UIViewController
    {
        private DataSource _dataSource;
        private MasterDialog _master;

        public StartDialog()
        {
            Title = "WTF";
        }

		UIButton button;

        public override void ViewDidLoad()
        {
            base.ViewDidLoad();

            button = new UIButton(UIButtonType.Custom);
            button.SetTitle("Open", UIControlState.Normal);
            button.BackgroundColor = UIColor.Green;
            button.Frame = new System.Drawing.RectangleF(20, 150, 280, 44);

            Add(button);

            button.TouchDown += OpenMasterDialog;
			Console.WriteLine (RetainCount);
        }

		UINavigationController nav; 

        private void OpenMasterDialog(object sender, EventArgs arguments)
        {
            _dataSource = new DataSource();

            _master = new MasterDialog();
            _master.DataSource = _dataSource;
            _master.OnDialogClosed += HandleOnDialogClosed;

            _master.SetViewControllers(
                new [] { _dataSource.GetViewController(1) }, 
                UIPageViewControllerNavigationDirection.Forward, 
                false, 
                null
            );

			nav = new UINavigationController (_master);
            NavigationController.PresentViewController(
				nav, 
                true, 
                null
            );
        }

        private void HandleOnDialogClosed(object sender, EventArgs e)
        {
            _dataSource.Dispose();
            _dataSource = null;

            Console.WriteLine("Before: " + _master.ChildViewControllers.Length +
                "/" + _master.ViewControllers.Length + ")");

            var childs = _master
                .ChildViewControllers.ToList()
                    .Union(_master.ViewControllers);

            foreach (UIViewController child in childs)
            {
                child.RemoveFromParentViewController();
                child.Dispose();
            }

            Console.WriteLine("After: " + _master.ChildViewControllers.Length + 
                "/" + _master.ViewControllers.Length + ")");

            _master.OnDialogClosed -= HandleOnDialogClosed;

            _master.Dispose();
            _master = null;
			// if you comment the next two lines HeatShot will report DetailDialog (after open/close)
			nav.Dispose ();
			nav = null;
        }
    }
}