private void DeleteItems(object sender, RoutedEventArgs e)
 {
     if (MasterListView.SelectedIndex != -1)
     {
         List <Smartphone> selectedItems = new List <Smartphone>();
         var mobileService = new ServicioDatos();
         foreach (Smartphone sm in MasterListView.SelectedItems)
         {
             selectedItems.Add(sm);
         }
         foreach (Smartphone sm in selectedItems)
         {
             Smartphones.Remove(sm);
             mobileService.DeleteSmartphone(sm);
         }
         if (MasterListView.Items.Count > 0)
         {
             MasterListView.SelectedIndex = 0;
             smartphoneSeleccionado       = MasterListView.SelectedItem as Smartphone;
         }
         else
         {
             DetailContentPresenter.Visibility = Visibility.Collapsed;
         }
     }
 }
        private void DeleteItem(object sender, RoutedEventArgs e)
        {
            if (smartphoneSeleccionado != null)
            {
                var mobileService = new ServicioDatos();
                Smartphones.Remove(smartphoneSeleccionado);
                mobileService.DeleteSmartphone(smartphoneSeleccionado);

                if (MasterListView.Items.Count > 0)
                {
                    MasterListView.SelectedIndex = 0;
                    smartphoneSeleccionado       = MasterListView.SelectedItem as Smartphone;
                }
                else
                {
                    DetailContentPresenter.Visibility = Visibility.Collapsed;
                    smartphoneSeleccionado            = null;
                }
            }
        }