トゥームストーンの後で、ページの状態をアプリの標準ページに復元する方法があるかどうか疑問に思っています。たとえば、ユーザーがページ 2 にいるときにアプリが廃棄された場合、復元されたページは常にページ 1 になります。アプリでページ 2 からデータを復元する方法に問題があり、この方法を代替手段として使用することを考えています。問題。
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();
}
}
私の問題は、tobstone 中に currentFeed を保存する方法がわからないことです。アプリがアクティブ化されるたびに、currentFeed は null になります。私は多くの解決策を試しましたが、結果はありませんでした。
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
}
}
これは私の app.xaml.cs であり、変更はありません。このコードでは、トゥームストーンはメインページと詳細ページでは正常に機能しますが、(もちろん) フィードページでは機能しません。