async void SubmitLogin(object sender, EventArgs args) { if (loading.IsRunning == false) { loading.IsRunning = true; Console.WriteLine("login action"); List <ValidationModel> validations = new List <ValidationModel>(); List <ConstraintsModel> constraintsModel = new List <ConstraintsModel>(); constraintsModel.Add(new ConstraintsModel(Constants.NOT_EMPTY_DATA)); validations.Add(new ValidationModel("Usuario:", username.Text, constraintsModel)); validations.Add(new ValidationModel("Contraseña:", password.Text, constraintsModel)); var validationResult = FormValidation.ValidateFields(validations, this); if (validationResult) { if (await App.restServices.login(username.Text, password.Text)) { loading.IsRunning = false; await Navigation.PushAsync(new Menu()); } else { loading.IsRunning = false; } } else { loading.IsRunning = false; } } }