public ViewModelLocator()
        {
            myNavigationService = new MyNavigationService();

            appViewModel          = new AppViewModel(myNavigationService);
            logInViewModel        = new LogInViewModel(myNavigationService);
            menyuViewModel        = new MenyuViewModel(myNavigationService);
            tripsViewModel        = new TripsViewModel(myNavigationService);
            registrationViewModel = new RegistrationViewModel(myNavigationService);
            weatherViewModel      = new WeatherViewModel(myNavigationService);
            ticketsPDFViewModel   = new TicketsPDFViewModel(myNavigationService);
            citiesViewModel       = new CitiesViewModel(myNavigationService);
            introViewModel        = new IntroViewModel(myNavigationService);
            mapViewModel          = new MapViewModel(myNavigationService);
            searchInfoViewModel   = new SearchInfoViewModel(myNavigationService);
            ticketsViewModel      = new TicketsViewModel(myNavigationService);

            myNavigationService.Register <LogInViewModel>(logInViewModel);
            myNavigationService.Register <MenyuViewModel>(menyuViewModel);
            myNavigationService.Register <TripsViewModel>(tripsViewModel);
            myNavigationService.Register <RegistrationViewModel>(registrationViewModel);
            myNavigationService.Register <WeatherViewModel>(weatherViewModel);
            myNavigationService.Register <TicketsPDFViewModel>(ticketsPDFViewModel);
            myNavigationService.Register <CitiesViewModel>(citiesViewModel);
            myNavigationService.Register <IntroViewModel>(introViewModel);
            myNavigationService.Register <MapViewModel>(mapViewModel);
            myNavigationService.Register <SearchInfoViewModel>(searchInfoViewModel);
            myNavigationService.Register <TicketsViewModel>(ticketsViewModel);

            //myNavigationService.Register("LogIn", logInViewModel);
            //myNavigationService.Register("Menyu", menyuViewModel);
            //myNavigationService.Register("Trips", tripsViewModel);
            //myNavigationService.Register("Registration", registrationViewModel);

            //myNavigationService.Navigate<LogInViewModel>();
            myNavigationService.Navigate <IntroViewModel>();
            //myNavigationService.Navigate<TicketsPDFViewModel>();
            //myNavigationService.Navigate<TripsViewModel>();

            //myNavigationService.Navigate("LogIn");
        }