如何访问现有AppBarButton并将其禁用

有没有办法访问现有数据库 AppBarButton 当我在除主页之外的特定页面上时,是否以编程方式禁用它?

<CommandBar Grid.Row="0">
    <CommandBar.Content>
        <Button 
            Style="{StaticResource NavigationBackButtonNormalStyle}" 
            Name="BackButton" 
            VerticalAlignment="Top" 
            Click="Back_Click"/>
    </CommandBar.Content>

    <AppBarButton Icon="Mail" Name="ContactUs"/>
</CommandBar>

使现代化

主页

public sealed partial class MainPage : Page
{
    public static AppBarButton MyAppBarButton;

    public MainPage()
    {
        this.InitializeComponent();

        Current = this;

        Frame_Main.Navigate(typeof(Frame1));

        MyAppBarButton = AppBarButtonSettings;
    }

    public static MainPage Current;

    private void Back_Click(object sender, RoutedEventArgs e)
    {
        On_BackRequested();
    }

    private bool On_BackRequested()
    {
        if (Frame_Main.CanGoBack)
        {
            Frame_Main.GoBack();
            return true;
        }
        return false;
    }

    private void BackInvoked(KeyboardAccelerator sender, KeyboardAcceleratorInvokedEventArgs args)
    {
        On_BackRequested();
        args.Handled = true;
    }

    private void AppBarButtonContactUs_Click(object sender, RoutedEventArgs e)
    {
        Frame_Main.Navigate(typeof(ContactUs));
    }
}

联系我们页面

public sealed partial class ContactUs: Page
{
    public ContactUs()
    {
        this.InitializeComponent();
    }

    protected override void OnNavigatedTo(NavigationEventArgs e)
    {
        MainPage.Current.BackButton.Visibility = Visibility.Visible;
        MainPage.Current.BackButton.IsEnabled = true;

        MainPage.MyAppBarButton.IsEnabled = false;
    }
}