private void Login() { if (string.IsNullOrWhiteSpace(UserName) || string.IsNullOrWhiteSpace(Password)) { PageService.DisplayAlert("Alert", "Enter all Values", "Ok"); return; } var customer = Reader.GetCustomerFromUserId(UserName, Password); if (customer != null) { PageService.PushAsync(new OrderPage(customer)); } else { PageService.DisplayAlert("Error", "Invalid User", "Ok"); } }