public RootPage()
        {
            MainTabView    = new TabView();
            DailyView      = new DailyView();
            ArticleView    = new ArticleView();
            CollectionView = new CollectionView();

            AndroidToolBarBinder.SetMiddleText(this, TabBarText[index]);

            Children = new List <TabViewChildren>()
            {
                new TabViewChildren()
                {
                    Text = TabBarText[0],
                    UnSelectTextColor        = Color.Gray,
                    UnSelectImageSource      = "daily_24dp.png",
                    SelectedImageSource      = "daily_24dp.png",
                    SelectedTextColor        = TabBarColorFilter,
                    UnSelectImageColorFilter = Color.Gray,
                    SelectedImageColorFilter = TabBarColorFilter,
                    View = DailyView,
                },
                new TabViewChildren()
                {
                    Text = TabBarText[1],
                    UnSelectTextColor        = Color.Gray,
                    UnSelectImageSource      = "form_24dp.png",
                    SelectedImageSource      = "form_24dp.png",
                    SelectedTextColor        = TabBarColorFilter,
                    UnSelectImageColorFilter = Color.Gray,
                    SelectedImageColorFilter = TabBarColorFilter,
                    View = ArticleView,
                },
                new TabViewChildren()
                {
                    Text = TabBarText[2],
                    UnSelectTextColor        = Color.Gray,
                    UnSelectImageSource      = "collection_24dp.png",
                    SelectedImageSource      = "collection_24dp.png",
                    SelectedTextColor        = TabBarColorFilter,
                    UnSelectImageColorFilter = Color.Gray,
                    SelectedImageColorFilter = TabBarColorFilter,
                    View = CollectionView,
                },
            };
            MainTabView.AddChildrenViews(Children);
            MainTabView.SelectedChanged += Handle_SelectedChanged;

            Content = MainTabView;
        }
 async void Handle_SelectedChanged(object sender, TabViewChangedEventArgs e)
 {
     index = e.Index;
     AndroidToolBarBinder.SetMiddleText(this, TabBarText[index]);
     if (index == 2)
     {
         var toolBar = new ToolbarItem()
         {
             Text = "清空"
         };
         toolBar.Clicked += ToolBar_Clicked;
         this.ToolbarItems.Add(toolBar);
         await CollectionView.ViewModel.Refresh();
     }
     else
     {
         if (this.ToolbarItems.Count == 0)
         {
             return;
         }
         this.ToolbarItems[0].Clicked -= ToolBar_Clicked;
         this.ToolbarItems.Clear();
     }
 }
 public SecondPage()
 {
     InitializeComponent();
     this.BindingContext = new SecondViewModel();
     AndroidToolBarBinder.SetMiddleText(this, "Second Page");
 }