Dismissable modal controller for Xamarin. By inheriting it, your presented controller can be dismissed by tapping outside its view.

DismissableModalController.cs

using System;
using MonoTouch.UIKit;

namespace Danyal.Xamarin.iOS
{
  	public class DismissableModalController : UIViewController
	{
		protected UITapGestureRecognizer _dismissRecognizer;

		public DismissableModalController ()
		{
			_dismissRecognizer = new UITapGestureRecognizer (OnTapOutside);
			_dismissRecognizer.NumberOfTapsRequired = 1u;
			_dismissRecognizer.CancelsTouchesInView = false;
		}

		public override void ViewDidAppear (bool animated)
		{
			base.ViewDidAppear (animated);
			View.Window.AddGestureRecognizer (_dismissRecognizer);
		}

		private void OnTapOutside(UITapGestureRecognizer recogniser)
		{
			if (recogniser.State == UIGestureRecognizerState.Ended)
			{
				var window = View.Window;
				DismissViewController (true, () => window.RemoveGestureRecognizer (_dismissRecognizer));
			}
		}
	}
}