Question

I have a problem with “re-init” MainWindow objects settings. I thought that OnNavigatedTo will call after suspending too and I have some code in MainWindow like:
protected override void OnNavigatedTo(NavigationEventArgs e)
{
object.value = initValue;
}

But it wasn’t called after suspending. So how can do this after suspending?

Answer 1

If you use the default templates that come with VS2012, you’ll see following code in the App.xaml.cs file:

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

        // ... took out some code here

            if (args.PreviousExecutionState == ApplicationExecutionState.Terminated)
            {
                // Restore the saved session state only when appropriate
                try
                {
                    await SuspensionManager.RestoreAsync();
                }
                catch (SuspensionManagerException)
                {
                    //Something went wrong restoring state.
                    //Assume there is no state and continue
                }
            }

        // ... took out some more code here    

        Window.Current.Activate();
    }

The possible values for ApplicationExecutionState are

public enum ApplicationExecutionState
{
    // Summary:
    //     The app is not running.
    NotRunning = 0,
    //
    // Summary:
    //     The app is running.
    Running = 1,
    //
    // Summary:
    //     The app is suspended.
    Suspended = 2,
    //
    // Summary:
    //     The app was terminated after being suspended.
    Terminated = 3,
    //
    // Summary:
    //     The app was closed by the user.
    ClosedByUser = 4,
}

So just add another if statement for

if (args.PreviousExecutionState == ApplicationExecutionState.Suspended)

to execute the code you want to execute after a suspended state.

To restore a previous state in the pages itself, use the LoadState and SaveState methods that are defined on the LayoutAwarePage base class of each page (or implement your own state management). The templates that come with VS2012 (eg. the Grid application) already uses all these tricks for state management and are a good way to get started.

protected override void LoadState(Object navigationParameter, Dictionary<String, Object> pageState)
protected override void SaveState(Dictionary<String, Object> pageState)