public App()
        {
            InitializeComponent();

            // determine page to navigate to
            var tokenClient = new TokenClient();
            var isLoggedIn  = tokenClient.IsLoggedIn();

            NavigationPage mainPage;

            if (isLoggedIn)
            {
                mainPage = new NavigationPage(new RootPage())
                {
                    BarBackgroundColor = Color.FromHex("#E5E5E2")
                };
            }
            else
            {
                mainPage = new NavigationPage(new SignIn())
                {
                    BarBackgroundColor = Color.FromHex("#E5E5E2")
                };
            }

            MainPage = mainPage;
        }