/// <summary>
/// Invoked when this page is about to be displayed in a Frame.
/// </summary>
/// <param name="e">Event data that describes how this page was reached. The Parameter
/// property provides the group to be displayed.</param>
protected override void OnNavigatedTo(NavigationEventArgs e)
{
// Returning to a cached page through navigation shouldn't trigger state loading
if (this._pageKey != null) return;
var frameFacade = new FrameFacadeAdapter(this.Frame);
var frameState = SuspensionManager.SessionStateForFrame(frameFacade);
this._pageKey = "Page-" + frameFacade.BackStackDepth;
if (e.NavigationMode == NavigationMode.New)
{
// Clear existing state for forward navigation when adding a new page to the
// navigation stack
var nextPageKey = this._pageKey;
int nextPageIndex = frameFacade.BackStackDepth;
while (frameState.Remove(nextPageKey))
{
nextPageIndex++;
nextPageKey = "Page-" + nextPageIndex;
}
// Pass the navigation parameter to the new page
this.LoadState(e.Parameter, null);
}
else
{
// Pass the navigation parameter and preserved page state to the page, using
// the same strategy for loading suspended state and recreating pages discarded
// from cache
this.LoadState(e.Parameter, (Dictionary<String, Object>)frameState[this._pageKey]);
}
}
/// <summary>
/// Invoked when this page will no longer be displayed in a Frame.
/// </summary>
/// <param name="e">Event data that describes how this page was reached. The Parameter
/// property provides the group to be displayed.</param>
protected override void OnNavigatedFrom(NavigationEventArgs e)
{
var frameFacade = new FrameFacadeAdapter(this.Frame);
var frameState = SuspensionManager.SessionStateForFrame(frameFacade);
var pageState = new Dictionary<String, Object>();
this.SaveState(pageState);
frameState[_pageKey] = pageState;
}
private async Task<Frame> InitializeFrameAsync(IActivatedEventArgs args)
{
var 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();
var frameFacade = new FrameFacadeAdapter(rootFrame);
//Associate the frame with a SuspensionManager key
SuspensionManager.RegisterFrame(frameFacade, "AppFrame");
//Initialize MvvmAppBase common services
SuspensionManagerState = new SuspensionManagerState();
NavigationService = CreateNavigationService(frameFacade, SuspensionManagerState);
FlyoutService = new FlyoutService();
FlyoutService.FlyoutResolver = CreateFlyoutView;
// <snippet518>
SettingsCharmService = new SettingsCharmService(GetSettingsCharmItems, FlyoutService);
SettingsPane.GetForCurrentView().CommandsRequested += SettingsCharmService.OnCommandsRequested;
// </snippet518>
// Set a factory for the ViewModelLocator to use the default resolution mechanism to construct view models
ViewModelLocator.SetDefaultViewModelFactory(Resolve);
OnRegisterKnownTypesforSerialization();
if (args.PreviousExecutionState == ApplicationExecutionState.Terminated)
{
await SuspensionManager.RestoreSessionStateAsync();
}
OnInitialize(args);
if (args.PreviousExecutionState == ApplicationExecutionState.Terminated)
{
// Restore the saved session state and navigate to the last page visited
try
{
SuspensionManager.RestoreFrameState();
NavigationService.RestoreSavedNavigation();
}
catch (SuspensionManagerException)
{
// Something went wrong restoring state.
// Assume there is no state and continue
}
}
// Place the frame in the current Window
Window.Current.Content = rootFrame;
}
return rootFrame;
}