private async Task LoginCommandAsync() { if (IsBusy) { return; } try { IsBusy = true; var userService = new FirebaseService(); Result = await userService.LoginUsuario(Username, Password); if (Result) { MessagingCenter.Send <User>(this.User, "SucessoLogin"); } else { await Application.Current.MainPage.DisplayAlert("Erro", "Usuário/Senha inválido(s)", "Ok"); } } catch (Exception ex) { await Application.Current.MainPage.DisplayAlert("Erro", ex.Message, "Ok"); } finally { IsBusy = false; } }