private void HandleContentDialogPrimaryButtonClick(ContentDialog sender, ContentDialogButtonClickEventArgs args)
{
var selectedItem = AddComboBox.SelectedItem;
if (selectedItem == null)
{
return;
}
PlaylistViewModel selectedPlaylist = DebugHelper.CastAndAssert <PlaylistViewModel>(selectedItem);
selectedPlaylistId = selectedPlaylist.PlaylistId;
selectedPlaylist.AddSong(Song);
}