Hold execution after showing UIAlertView

// Displays a UIAlertView and returns the index of the button pressed.
public static Task ShowAlert (string title, string message, params string [] buttons)
{
    var tcs = new TaskCompletionSource ();
    var alert = new UIAlertView {
        Title = title,
        Message = message
    };
    foreach (var button in buttons)
        alert.AddButton (button);
    alert.Clicked += (s, e) => tcs.TrySetResult (e.ButtonIndex);
    alert.Show ();
    return tcs.Task;
}

Then you do instead:

int button = await ShowAlert ("Foo", "Bar", "Ok", "Cancel", "Maybe");

Source : http://stackoverflow.com/questions/19120841/yes-no-confirmation-uialertview