uwp-shop-analytics-sample/UWPShop.Client/App.xaml.cs

using System;

using UWPShop.Client.Services;

using Windows.ApplicationModel;
using Windows.ApplicationModel.Activation;
using Windows.UI.Xaml;

namespace UWPShop.Client
{
    /// <summary>
    /// Provides application-specific behavior to supplement the default Application class.
    /// </summary>
    sealed partial class App : Application
    {
        private Lazy<ActivationService> _activationService;
        private ActivationService ActivationService { get { return _activationService.Value; } }

        /// <summary>
        /// Initializes the singleton application object.  This is the first line of authored code
        /// executed, and as such is the logical equivalent of main() or WinMain().
        /// </summary>
        public App()
        {
            InitializeComponent();

            EnteredBackground += App_EnteredBackground;

            //Deferred execution until used. Check https://msdn.microsoft.com/library/dd642331(v=vs.110).aspx for further info on Lazy<T> class.
            _activationService = new Lazy<ActivationService>(CreateActivationService);
        }

        /// <summary>
        /// Invoked when the application is launched normally by the end user.  Other entry points
        /// will be used such as when the application is launched to open a specific file.
        /// </summary>
        /// <param name="e">Details about the launch request and process.</param>
        protected override async void OnLaunched(LaunchActivatedEventArgs e)
        {
            if (!e.PrelaunchActivated)
            {
                await ActivationService.ActivateAsync(e); 
            }
        }

        /// <summary>
        /// Invoked when the application is activated by some means other than normal launching.
        /// </summary>
        /// <param name="args">Event data for the event.</param>
        protected override async void OnActivated(IActivatedEventArgs args)
        {
            await ActivationService.ActivateAsync(args);
        }
            
        private async void App_EnteredBackground(object sender, EnteredBackgroundEventArgs e)
        {
            var deferral = e.GetDeferral();
            await Helpers.Singleton<SuspendAndResumeService>.Instance.SaveStateAsync();
            deferral.Complete();
        }
        private ActivationService CreateActivationService()
        {
            return new ActivationService(this, typeof(Views.MainPage), new Views.ShellPage());
        }
    }
}