protected async override void OnNavigatedTo(NavigationEventArgs e)
 {
     if (e.NavigationMode == NavigationMode.New || myFollowVideoVM == null)
     {
         await myFollowVideoVM.LoadFavorite();
     }
 }
        private async void pivot_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            if (pivot.SelectedItem == null)
            {
                return;
            }
            switch (pivot.SelectedIndex)
            {
            case 0:
                if (videoVM.Loading || videoVM.MyFavorite != null)
                {
                    return;
                }
                await videoVM.LoadFavorite();

                break;

            case 1:
                if (animeVM.Loading || animeVM.Follows != null)
                {
                    return;
                }
                await animeVM.LoadFollows();

                break;

            case 2:
                if (cinemaVM.Loading || cinemaVM.Follows != null)
                {
                    return;
                }
                await cinemaVM.LoadFollows();

                break;

            default:
                break;
            }
        }