public override void Disappearing()
 {
     _messageObserversController.StopObserving();
     base.Disappearing();
 }
 protected override void OnPause()
 {
     base.OnPause();
     _messageObserversController.StopObserving();
 }
 public override void ViewDisappeared()
 {
     base.ViewDisappeared();
     _messageObserversController.StopObserving();
 }