private async void Login()
        {
            try
            {
                ActivityIndicatorTitle = "Logging In. Please wait.";
                IsBusy = true;

                User userObject = PrismApplicationBase.Current.Container.Resolve(typeof(User)) as User;

                userObject.UserID   = _userId;
                userObject.Password = _password;
                userObject.UserName = await FirebaseService.GetUserNameAsync(_userId);

                if (!string.IsNullOrEmpty(await FirebaseService.LoginAsync(userObject)))
                {
                    await NavigationService.NavigateAsync("MainPage");
                }
                else
                {
                    await DialogService.DisplayAlertAsync("Log in failed !", "Incorrect ID or password. Please try again.", "OK");
                }
            }

            finally
            {
                IsBusy = false;
            }
        }