Question

我尝试将在Template10 on GitHub中实现shell的指令调整到辅助窗口中的shell，但它无效。

此代码：

await DispatcherWrapper.Current().DispatchAsync(async () =>
        {
                //The next line gets the exception
                var control = await BootStrapper.Current.NavigationService.OpenAsync(
                                                    typeof(MySecondaryShell), null, "My Secondary Function");
                control.Released += Control_Released;
                BootStrapper.Current.NavigationService.Navigate(typeof(MySecondaryPage));
    });

获得此异常：

E VUI 1808 16：12：27.203 D：\ SVN_Trunk \ Source \ Uwp \ Gui \ UwpMain \ ViewModels \ MyPrimaryShellViewModel.cs.275.MyFunction System.NullReferenceException：未将对象引用设置为对象的实例。在Uwp.Main.UwpMain_XamlTypeInfo.XamlUserType.ActivateInstance（）在Windows.UI.Xaml.Controls.Frame.Navigate（类型sourcePageType，Object参数，NavigationTransitionInfo infoOverride）在Template10.Services.NavigationService.FrameFacade.Navigate（类型页面，对象参数，NavigationTransitionInfo infoOverride）在Template10.Services.NavigationService.NavigationService.d__34.MoveNext（） ---从抛出异常的先前位置开始的堆栈跟踪结束--- 在System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）在System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）在Template10.Services.NavigationService.NavigationService.Navigate（类型页面，对象参数，NavigationTransitionInfo infoOverride）在Template10.Services.ViewService.ViewService。＆lt;＆gt; c__DisplayClass1_0。＆lt; b__0＆gt; d.MoveNext（） ---从抛出异常的先前位置开始的堆栈跟踪结束--- 在System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）在System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）在Template10.Services.ViewService.ViewService.d__1.MoveNext（） ---从抛出异常的先前位置开始的堆栈跟踪结束--- 在System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）在System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）在System.Runtime.CompilerServices.TaskAwaiter`1.GetResult（）在Uwp.Main.ViewModels.MyPrimaryShellViewModel。＆lt;＆gt; c__DisplayClass63_0。＆lt; b__0＆gt; d.MoveNext（）

MySecondaryShell构造如下：

public static HamburgerMenu HamburgerMenu => Instance.EmulatorHamburgerMenu;

    public MySecondaryShell(INavigationService navigationService)
    {
        this.InitializeComponent();
        HamburgerMenu.NavigationService = navigationService;
    }

当我用shell打开主窗口时，我创建了shell对象，然后将NavigationService分配给它。

但是当我打开一个辅助窗口时，我只是使用typeof（MySecondaryShell）作为参数调用NavigationService.OpenAsync。是不是在shell中没有正确设置NavigationService的问题？（通过阅读my last question中的Template10代码，我无法看到NavigationService的设置位置。）

我应该如何打开shell作为辅助窗口？

Answer 1

我应该如何打开shell作为辅助窗口？

问题是您尚未将navigationService传递给MySecondaryShell。然后MySecondaryShell将在没有navigationService的情况下初始化失败。你可以让你的shell如下。

public sealed partial class MyShell : Page
{
    public static MyShell Instance { get; set; }

    public static HamburgerMenu HamburgerMenu => Instance.MyHamburgerMenu;

    Services.SettingsServices.SettingsService _settings;
    public MyShell()
    {
        Instance = this;
        this.InitializeComponent();
        _settings = Services.SettingsServices.SettingsService.Instance;
        var service = BootStrapper.Current.NavigationServiceFactory(BootStrapper.BackButton.Attach, BootStrapper.ExistingContent.Exclude);          
        SetNavigationService(service);

    }  
    public void SetNavigationService(INavigationService navigationService)
    {
        MyHamburgerMenu.NavigationService = navigationService;
        HamburgerMenu.RefreshStyles(_settings.AppTheme, true);
        HamburgerMenu.IsFullScreen = _settings.IsFullScreen;
        HamburgerMenu.HamburgerButtonVisibility = _settings.ShowHamburgerButton ? Visibility.Visible : Visibility.Collapsed;
    }
}

<强>用法

await DispatcherWrapper.Current().DispatchAsync(async () =>
{
    var control = await BootStrapper.Current.NavigationService.OpenAsync(typeof(Views.MyShell), null, Guid.NewGuid().ToString());
    await control.CoreDispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
    {
        Views.MyShell.HamburgerMenu.NavigationService.Navigate(typeof(Views.TestPage));
    });

});

如何用shell打开辅助窗口？

1 个答案: