private async void Email_Unfocused(object sender, FocusEventArgs e) { Entry email = (Entry)FindByName("email"); bool result = await model.CheckEmail(email.Text); if (result) { email.TextColor = Color.Red; await Application.Current.MainPage.DisplayAlert("Greška", "Email već postoji !", "OK"); } else { email.TextColor = Color.Black; } }