告诉ActivityIndi​​cator展现自己，然后导航到另一个页面

Question

在Xamarin.Forms项目，我想告诉ActivityIndicator展现自己，然后导航到另一个页面

activityIndicatorObject = new ActivityIndicator() 
       { 
        HorizontalOptions = LayoutOptions.CenterAndExpand, 
        Color = Color.Red, 
        IsVisible = false, 
        IsRunning = false, 
        IsEnabled = false, 
        BindingContext = this, 
       }; 
ViewBookButton = new Button{ Text = "view book" }; 
ViewBookButton.Clicked += ViewBook; 
protected void ViewBook(Object sender,EventArgs e) 
      { 
       //Go To View Book Page 
       activityIndicatorObject .IsVisible = true; 
       activityIndicatorObject .IsRunning = true; 
       activityIndicatorObject .IsEnabled = true; 
       activityIndicatorObject .SetBinding(ActivityIndicator.IsVisibleProperty, "IsBusy"); 
       this.IsBusy = true; 
       Navigation.PushAsync(new BookPage()); 
       this.IsBusy = false; 
      } 

ActivityIndicator不显示？我如何让它显示？

Answer 1

据我所知，告诉ActivityIndicator显示你自己，然后导航到另一页。并且新页面没有自己的ActivityIndicator。我想建议你在OnAppearing方法BookPage中进行艰苦操作。

protected override void OnAppearing() 
{ 
    base.OnAppearing(); 

    activityIndicator.IsVisible = true; 

    // Some hard operations 

    activityIndicator.IsVisible = false; 
} 

或使用绑定的activityIndicator.IsVisible = true;