c# - 如何删除或隐藏特定页面中的工具栏项错误 : System. IndexOutOfRangeException:索引超出数组范围

Question

我正在尝试 Remove() 或 Clear() ToolbarItems。这是我在 MainPage.cs 中创建 ToolbarItem

的代码

public partial class MainPage : MasterDetailPage
{
   public ToolbarItem cCounter = new ToolbarItem() { Icon = "picture.png" };
   public ToolbarItem pPo = new ToolbarItem() { Text = "-" };

   public MainPage()
    {
        InitializeComponent();
        if (Device.OS == TargetPlatform.iOS)
        {
            provider.Clicked += iOS_Ppo_Clicked;
            ToolbarItems.Add(cCounter);
            ToolbarItems.Add(pPo);
        }
    }

    private void iOS_Ppo_Clicked(object sender, EventArgs e)
    { 
        OpenWindow();            
    }

    public async void OpenWindow()
    {
        if (await Common.WindowComands.CanOpenWindow<PPoPage>(Detail))
        {  
            page = new PPoPage(Page3.Allproviders);

            this.ToolbarItems.Clear(); // here I am getting error:Index was outside the bounds of the array 

            page.OnSelected += Page_OnSelected;
            await Detail.Navigation.PushAsync(page, false);             
        }   
    }
}

Edit: when I included this.ToolbarItems.Clear(); in OpenWindow method which initialise that another page opens and it works! Cleans all toolbar items but unfortunately shows this error:

System.IndexOutOfRangeException: Index was outside the bounds of the array.

如您所见，此项目应该仅在 iOS 中消失。这是我的页面类，我想在其中 Remove() 这些 ToolbarItems:

public partial class PPoPage : ContentPage
{
   public MainPage main { get; set; }

   private List<PPo> Pro;

   public PPoPage(List<PPo> po)
   {
      InitializeComponent();
      if (Device.OS == TargetPlatform.iOS)
      {
         Pro = po;
         CreateLayout();
         // HERE I WANT TO REMOVE TOOLBARITEMS FOR THIS PAGE
         this.ToolbarItem.Remove(main.cCounter); // here there is error
         this.ToolbarItems.Clear(); // this also doesn't work, because toolbar items still exist after this initialization.
      }
   }
}

在这门课上，我尝试了两种方法，但都没有用。感谢您的回答或建议。

Answer 1

我的任务是更改工具栏项的可见性，我创建了包含 ToolbarItems 集合包装器的基本内容页面。我的示例可以帮助您:

sample on git

some "tutorial" that I've posted on CodeReview