Xamarin Form: Ios Toast Notification - ios

Question

I have created a Toast notification in my Xamarin PCL project. I have created this control using this. As soon as this toast message disappears my app becomes blank. I cannot figure out why? no exception from any where??
In Portable:
namespace ABC
{
public interface IMessage
{
void LongAlert(string message);
void ShortAlert(string message);
}
}
In Droid:
public class MessageAndroid : IMessage
{
public void LongAlert(string message)
{
Toast.MakeText(Application.Context, message, ToastLength.Long).Show();
}
public void ShortAlert(string message)
{
Toast.MakeText(Application.Context, message, ToastLength.Short).Show();
}
}
In Windows 10:
public class ToastNotificationManagerRenderer : IMessage
{
public void LongAlert(string message)
{
var notificationXml = ToastNotificationManager.GetTemplateContent(ToastTemplateType.ToastText01);
var toeastElement = notificationXml.GetElementsByTagName("text");
toeastElement[0].AppendChild(notificationXml.CreateTextNode(message));
var toastNotification = new ToastNotification(notificationXml);
ToastNotificationManager.CreateToastNotifier().Show(toastNotification);
}
public void ShortAlert(string message)
{
var notificationXml = ToastNotificationManager.GetTemplateContent(ToastTemplateType.ToastText01);
var toeastElement = notificationXml.GetElementsByTagName("text");
toeastElement[0].AppendChild(notificationXml.CreateTextNode(message));
var toastNotification = new ToastNotification(notificationXml);
ToastNotificationManager.CreateToastNotifier().Show(toastNotification);
}
}
In Ios:
public class MessageIOS : IMessage
{
const double LONG_DELAY = 3.5;
const double SHORT_DELAY = 2.0;
NSTimer alertDelay;
UIAlertController alert;
public void LongAlert(string message)
{
ShowAlert(message, LONG_DELAY);
}
public void ShortAlert(string message)
{
ShowAlert(message, SHORT_DELAY);
}
void ShowAlert(string message, double seconds)
{
alertDelay = NSTimer.CreateScheduledTimer(seconds, (obj) =>
{
dismissMessage();
});
alert = UIAlertController.Create(null, message, UIAlertControllerStyle.Alert);
UIApplication.SharedApplication.KeyWindow.RootViewController.PresentViewController(alert, true, null);
}
void dismissMessage()
{
if (alert != null)
{
alert.DismissViewController(true, null);
}
if (alertDelay != null)
{
alertDelay.Dispose();
}
}
}
For Ios: I have tried this plugin also.MessageBarLib. Code same as above in portable but in Ios -
public void ShortAlert(string message)
{
MessageBarManager.SharedInstance.ShowMessage("Success", message, MessageType.Success);
}
But after exiting from above function, my app closes.

Answer 1

Based off of your comments and the code, I suspect that the dismissMessage()' is clearing all of the UIViewControllers that were put onto the stack by the 'PresentingViewController'. I suspect it's a bit of a bug, but If you try:
PresentingViewController.DismissViewController(true, null);
Instead of
alert.DismissViewController(true, null);
I suspect it should work correctly. If not then we could do with knowing a bit more about the design pattern you use in your iOS project to determine if you are presenting 'UIViewControllers' properly.

Answer 2

I tried this for IOS:-
private const int Margin = 30;
private const int Height = 40;
private const int Width = 400;
private NSTimer _timer;
public void ShowAlert(string message)
{
var toast = new MessageIOS();
toast.Show(UIApplication.SharedApplication.KeyWindow.RootViewController.View, message);
}
public MessageIOS()
{
_view = new UIView(new CGRect(0, 0, 0, 0))
{
BackgroundColor = UIColor.FromRGB(0, 175, 240)
};
_view.Layer.CornerRadius = (nfloat)20.0;
_label = new UILabel(new CGRect(0, 0, 0, 0))
{
TextAlignment = UITextAlignment.Center,
TextColor = UIColor.White
};
_view.AddSubview(_label);
}
public void Show(UIView parent, string message)
{
if (_timer != null)
{
_timer.Invalidate();
_view.RemoveFromSuperview();
}
_view.Alpha = (nfloat)0.7;
_view.Frame = new CGRect(
(parent.Bounds.Width - Width) / 2,
parent.Bounds.Height - Height - Margin,
Width,
Height);
_label.Frame = new CGRect(0, 0, Width, Height);
_label.Text = message;
parent.AddSubview(_view);
var wait = 10;
_timer = NSTimer.CreateRepeatingScheduledTimer(TimeSpan.FromMilliseconds(100), delegate {
if (_view.Alpha <= 0)
{
_timer.Invalidate();
_view.RemoveFromSuperview();
}
else
{
if (wait > 0)
{
wait--;
}
else
{
_view.Alpha -= (nfloat)0.05;
}
}
});
}