public MasterDetailPage1Detail()
        {
            InitializeComponent();
            CustomListView listView = new CustomListView();

            ImageService.Instance.Config.MaxMemoryCacheSize = 1000;
            this.Appearing += async(sender, e) =>
            {
                images = await DependencyService.Get <IPicturePicker>().GetImageStreamAsync();
            };
            listView.ItemsSource            = images;
            listView.ItemTemplate           = new DataTemplate(typeof(CachedImageCell));
            listView.IsPullToRefreshEnabled = true;
            listView.HasUnevenRows          = true;

            listView.Refreshing += delegate {
                listView.ItemsSource = images;
                listView.EndRefresh();
            };
            Content = listView;
        }