public Task <object> ShowModal()
        {
            var tcs = new TaskCompletionSource <object>();

            UIApplication.SharedApplication.InvokeOnMainThread(new NSAction(() =>
            {
                var modal       = new AsyncModalViewController();
                modal.Dismissed = tcs.SetResult;
                PresentViewController(modal, true, null);
            }));

            return(tcs.Task);
        }
        public Task<object> ShowModal() 
        {
            var tcs = new TaskCompletionSource<object>();

            UIApplication.SharedApplication.InvokeOnMainThread(new NSAction(() =>
            {
                var modal = new AsyncModalViewController();
                modal.Dismissed = tcs.SetResult;
                PresentViewController(modal, true, null);
            }));
           
            return tcs.Task;
        }