private void AddOrRemoveFav( object sender, TappedRoutedEventArgs e ) { BookItem B = ( ( sender as FrameworkElement ).DataContext ) as BookItem; BookStorage BS = new BookStorage(); if ( B.IsFav ) { BS.RemoveBook( B.Id ); B.IsFav = false; } else { BS.SaveBook( B.Id, B.Title, B.RecentUpdateRaw, B.LatestSection ); B.IsFav = true; } }