如何管理应用状态

Question

假设我以这种方式设计了页面导航：

P(1) -> goto P(2) -> goto P(3) 并在 P(3) 处，用户单击 Home 按钮（Microsoft 按钮）

a) 应用重新启动时如何返回 p(3)？

谢谢

--- 更新

我需要在这个活动上做什么？

受保护的覆盖无效 OnLaunched(LaunchActivatedEventArgs args) { Frame rootFrame = Window.Current.Content as Frame; // 当 Window 已经有内容时，不要重复应用初始化， // 只需确保窗口处于活动状态 if (rootFrame == null) { // 创建一个 Frame 作为导航上下文并导航到第一页 rootFrame = new Frame(); if (args.PreviousExecutionState == ApplicationExecutionState.Terminated) { //TODO：从先前挂起的应用程序加载状态 } // 将框架放置在当前窗口中 Window.Current.Content = rootFrame； } if (rootFrame.Content == null) { // 当导航堆栈未恢复时，导航到第一页， // 通过传递所需信息作为导航来配置新页面 // 范围 if (!rootFrame.Navigate(typeof(MainPage), args.Arguments)) { throw new Exception("创建初始页面失败"); } } // 确保当前窗口处于活动状态 Window.Current.Activate(); }

Answer 1

您可以使用本地设置存储在每个页面的OnNavigatedTo事件中打开的最后一个页面。

protected override void OnNavigatedTo(NavigationEventArgs e)
{
    ApplicationData.Current.LocalSettings.Values["LastPage"] = this.GetType().ToString();
}

在 App.xaml.cs 的OnLaunched(..) 事件之后，您检查哪个是最后打开的页面。据此，您可以导航它。

protected override void OnLaunched(LaunchActivatedEventArgs args)
{
    Frame rootFrame = Window.Current.Content as Frame;

    // Do not repeat app initialization when the Window already has content,
    // just ensure that the window is active
    if (rootFrame == null)
    {
        // Create a Frame to act as the navigation context and navigate to the first page
        rootFrame = new Frame();

        if (args.PreviousExecutionState == ApplicationExecutionState.Terminated)
        {
            //TODO: Load state from previously suspended application
        }

        // Place the frame in the current Window
        Window.Current.Content = rootFrame;
    }

    if (rootFrame.Content == null)
    {
        // When the navigation stack isn't restored navigate to the first page,
        // configuring the new page by passing required information as a navigation
        // parameter

        if (ApplicationData.Current.LocalSettings.Values["LastPage"] != null)
        {
            Type t = Type.GetType((string)ApplicationData.Current.LocalSettings.Values["LastPage"]);
            if (!rootFrame.Navigate(t, args.Arguments))
            {
                throw new Exception("Failed to create initial page");
            }
        }

        else
        {
            if (!rootFrame.Navigate(typeof(MainPage), args.Arguments))
            {
                throw new Exception("Failed to create initial page");
            }
        }
    }
    // Ensure the current window is active
    Window.Current.Activate();
}