private async void DeleteBarButtonClick(object sender, RoutedEventArgs e)
{
DeleteAppBarButton.Visibility = Visibility.Collapsed;
ViewModel1.RemoveListItem(ViewModel1.SelectedItem);
ViewModel1.SelectedItem = null;
Assignment();
TileService.UpdateTile();
ToastService.DeleteNotify();
await new MessageDialog("Delete successfully！").ShowAsync();
}
private async void MenuFlyoutDelete_Click(object sender, RoutedEventArgs e)
{
ViewModel1.SelectedItem = (sender as MenuFlyoutItem).DataContext as ListItem;
ViewModel1.RemoveListItem(ViewModel1.SelectedItem);
await new MessageDialog("Delete successfully！").ShowAsync();
Frame rootFrame = Window.Current.Content as Frame;
rootFrame.Navigate(typeof(MainPage));
}