private async void Button_Clicked(object sender, EventArgs e) { bool loggedin = true;// Here Put The Boolean Method that Checks If He's Logged In if (loggedin) { bool yesno = await DisplayAlert("Sending Request", "Are You Sure You Want To Request This Book ?", "Yes", "No");// Depending On His Answer if (yesno) { var Req = new Request() { UserEmail = "EMAIL", BookISBN = bk.ISBN, BookTitle = bk.Title, dateTime = DateTime.Now, }; await FirebaseHelper.AddRequest(Req); await DisplayAlert("Success", "Your Request Has Been Sent", "Ok"); } } else { await PopupNavigation.Instance.PushAsync(new Login()); } }