simple MessageBox para Xamarin ios

MessageBox iOs

public static class MessageBox
	{

		public static void Show(string title, string message, MessageBoxButton buttons, Action positiveCallback, Action negativeCallback)
		{               
			UIAlertView alert = BuildAlert(title, message, buttons);
			alert.Clicked += (sender, buttonArgs) => 
			{
				if (buttonArgs.ButtonIndex == 0) 
				{
					positiveCallback();
				}
				else
				{
					negativeCallback();
				}
			};

			NSThread.MainThread.InvokeOnMainThread (alert.Show);
		}

		public static void Show(string title, string message)
		{               
			UIAlertView alert = BuildAlert(title, message, MessageBoxButton.OK);
			NSThread.MainThread.InvokeOnMainThread(alert.Show);
		}

		public static void Show(string title, string message, MessageBoxButton buttons, Action positiveCallback)
		{               
			UIAlertView alert = BuildAlert(title, message, buttons);
			alert.Clicked += (sender, buttonArgs) => 
			{
				if (buttonArgs.ButtonIndex == 0) 
				{
					positiveCallback();
				}
			};

			NSThread.MainThread.InvokeOnMainThread(alert.Show);
		}

		static UIAlertView BuildAlert(string title, string message, MessageBoxButton buttons)
		{
			switch(buttons)
			{
			case MessageBoxButton.OK :
				return new UIAlertView(title, message, null, "Ok", null);
			case MessageBoxButton.OKCancel :
				return new UIAlertView(title, message, null, "Ok", "Cancel");
			case MessageBoxButton.YesNo :
				return new UIAlertView(title, message, null, "Yes", "No");
			default:
				return new UIAlertView(title, message, null, "Ok", null);
			}
			//throw new NotImplementedException(buttons.ToString());
		}       

	}