App.xaml.cs

using System;
using Windows.ApplicationModel;
using Windows.ApplicationModel.Activation;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Navigation;
using ReactiveCalculator.UWP;
using Xamarin.Forms;
using Application = Windows.UI.Xaml.Application;
using Frame = Windows.UI.Xaml.Controls.Frame;


namespace ReactiveCalculator.UWP
{
    sealed partial class App : Application
    {
        public App()
        {
            this.InitializeComponent();
            this.Suspending += this.OnSuspending;
        }


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

            if (rootFrame == null)
            {
                rootFrame = new Frame();

                rootFrame.NavigationFailed += this.OnNavigationFailed;
                Forms.Init(e);
                Window.Current.Content = rootFrame;
            }

            if (rootFrame.Content == null)
                rootFrame.Navigate(typeof(MainPage), e.Arguments);

            Window.Current.Activate();
        }


        void OnNavigationFailed(object sender, NavigationFailedEventArgs e)
            => throw new Exception("Failed to load Page " + e.SourcePageType.FullName);


        void OnSuspending(object sender, SuspendingEventArgs e)
        {
            e
                .SuspendingOperation
                .GetDeferral()
                .Complete();
        }
    }
}