public async Task OnListItemTapped(NotificationViewModel vm)
        {
            switch (vm.NotificationType)
            {
            // depending  on notification type and other entries navigate to new page, or do something
            case NotificationType.Feature:
                // should be actioned by button press
                break;

            case NotificationType.FeatureUpdate:
                // should be actioned by button press
                break;

            case NotificationType.Offer:
                if (!string.IsNullOrWhiteSpace(vm.UrlLink))
                {
                    // Navigate to url in WebView
                }
                break;

            default:
                if (!string.IsNullOrWhiteSpace(vm.Message))
                {
                    // Navigate to Message page
                }
                break;
            }

            if (vm.IsUnread)
            {
                // change state to read
                vm.IsUnread = false;
                // update stored entry to persist the state (note: Notification has a Read property, not UnRead)
                await Settings.UpdateNotificationAsync(vm.Id, true);
            }
        }
 public void AddNotification(NotificationViewModel notification)
 {
     _notificationCollection.Add(notification);
     OnPropertyChanged <ObservableCollection <NotificationViewModel> >(nameof(NotificationCollection));
 }