/// <summary>
/// Invoked when application execution is being suspended. Application state is saved
/// without knowing whether the application will be terminated or resumed with the contents
/// of memory still intact.
/// </summary>
/// <param name="sender">The source of the suspend request.</param>
/// <param name="e">Details about the suspend request.</param>
protected override async void OnSuspending(SuspendingEventArgs args)
{
// Obtains the registered application state service
IApplicationStateService stateService = this.GetService <IApplicationStateService>();
var deferral = args.SuspendingOperation.GetDeferral();
await stateService.SaveAsync();
deferral.Complete();
}