我想知道在墓碑之后是否有任何方法可以将页面状态恢复到应用程序中的标准页面。例如，如果应用程序在用户位于第 2 页时被墓碑化，则恢复的页面将始终是第 1 页。我在如何从应用程序的第 2 页恢复数据时遇到问题，我认为这种方法可以解决这个问题问题。
public FeedPage()
{
InitializeComponent();
this.Loaded += new RoutedEventHandler(FeedPage_Loaded);
performanceProgressBar.Visibility = System.Windows.Visibility.Collapsed;
LoadFeed();
}
private void LoadFeed()
{
FrameworkElement root = Application.Current.RootVisual as FrameworkElement;
var currentFeed = root.DataContext as FeedViewModel;
WebClient client = new WebClient();
performanceProgressBar.IsIndeterminate = true;
performanceProgressBar.Visibility = System.Windows.Visibility.Visible;
client.DownloadStringCompleted += new DownloadStringCompletedEventHandler(client_DownloadStringCompleted);
client.DownloadStringAsync(new Uri(currentFeed.FeedUrl));
this.DataContext = currentFeed;
ApplicationBar.IsVisible = false;
}
...
private void FeedPage_Loaded(object sender, RoutedEventArgs e)
{
if (!App.ViewModel.IsDataLoaded)
{
App.ViewModel.LoadData();
}
}
我的问题是我现在不知道如何在 tobstone 时存储 currentFeed。每次激活应用程序时，currentFeed 都是空的。我尝试了很多解决方案，但没有结果。
public partial class App : Application
{
private static MainViewModel viewModel = null;
/// <summary>
/// A static ViewModel used by the views to bind against.
/// </summary>
/// <returns>The MainViewModel object.</returns>
public static MainViewModel ViewModel
{
get
{
// Delay creation of the view model until necessary
if (viewModel == null)
viewModel = new MainViewModel();
return viewModel;
}
}
/// <summary>
/// Provides easy access to the root frame of the Phone Application.
/// </summary>
/// <returns>The root frame of the Phone Application.</returns>
public PhoneApplicationFrame RootFrame { get; private set; }
/// <summary>
/// Constructor for the Application object.
/// </summary>
public App()
{
// Global handler for uncaught exceptions.
UnhandledException += Application_UnhandledException;
// Show graphics profiling information while debugging.
if (System.Diagnostics.Debugger.IsAttached)
{
// Display the current frame rate counters.
Application.Current.Host.Settings.EnableFrameRateCounter = true;
// Show the areas of the app that are being redrawn in each frame.
//Application.Current.Host.Settings.EnableRedrawRegions = true;
// Enable non-production analysis visualization mode,
// which shows areas of a page that are being GPU accelerated with a colored overlay.
//Application.Current.Host.Settings.EnableCacheVisualization = true;
}
// Standard Silverlight initialization
InitializeComponent();
// Phone-specific initialization
InitializePhoneApplication();
}
// Code to execute when the application is launching (eg, from Start)
// This code will not execute when the application is reactivated
private void Application_Launching(object sender, LaunchingEventArgs e)
{
}
// Code to execute when the application is activated (brought to foreground)
// This code will not execute when the application is first launched
private void Application_Activated(object sender, ActivatedEventArgs e)
{
}
// Code to execute when the application is deactivated (sent to background)
// This code will not execute when the application is closing
private void Application_Deactivated(object sender, DeactivatedEventArgs e)
{
}
// Code to execute when the application is closing (eg, user hit Back)
// This code will not execute when the application is deactivated
private void Application_Closing(object sender, ClosingEventArgs e)
{
}
// Code to execute if a navigation fails
private void RootFrame_NavigationFailed(object sender, NavigationFailedEventArgs e)
{
if (System.Diagnostics.Debugger.IsAttached)
{
// A navigation has failed; break into the debugger
System.Diagnostics.Debugger.Break();
}
}
// Code to execute on Unhandled Exceptions
private void Application_UnhandledException(object sender, ApplicationUnhandledExceptionEventArgs e)
{
if (System.Diagnostics.Debugger.IsAttached)
{
// An unhandled exception has occurred; break into the debugger
System.Diagnostics.Debugger.Break();
}
}
#region Phone application initialization
// Avoid double-initialization
private bool phoneApplicationInitialized = false;
// Do not add any additional code to this method
private void InitializePhoneApplication()
{
if (phoneApplicationInitialized)
return;
// Create the frame but don't set it as RootVisual yet; this allows the splash
// screen to remain active until the application is ready to render.
RootFrame = new PhoneApplicationFrame();
RootFrame.Navigated += CompleteInitializePhoneApplication;
// Handle navigation failures
RootFrame.NavigationFailed += RootFrame_NavigationFailed;
// Ensure we don't initialize again
phoneApplicationInitialized = true;
}
// Do not add any additional code to this method
private void CompleteInitializePhoneApplication(object sender, NavigationEventArgs e)
{
// Set the root visual to allow the application to render
if (RootVisual != RootFrame)
RootVisual = RootFrame;
// Remove this handler since it is no longer needed
RootFrame.Navigated -= CompleteInitializePhoneApplication;
}
#endregion
}
}
这是我的 app.xaml.cs 现在没有任何更改。使用此代码，墓碑在主页和详细信息页面中可以正常工作，但在提要页面中（当然）不能正常工作。