区分按钮单击 xamarin.forms

Question

您好，我的 xamarin.forms 应用程序中有四个按钮。每次单击按钮都会在弹出窗口中打开一个列表视图。我试图在每次单击按钮时打开相同的弹出页面。我正在使用消息中心返回列表视图选定项返回按钮页面。我卡住的地方是如何区分弹出页面中的按钮点击？我应该使用标志还是其他东西？

我的按钮页面

  void Button1_Tapped(object sender, EventArgs e)
        {


            PopupNavigation.PushAsync(new AnswerPopup(tranzaction));

            MessagingCenter.Subscribe<MyMessage>(this, "AnsData", (value) =>
            {
                string receivedData = value.Myvalue;
                Answer1.Text = receivedData;
            });
        }

        void Button2_Tapped(object sender, EventArgs e)
        {

            PopupNavigation.PushAsync(new AnswerPopup(tranzaction));

            MessagingCenter.Subscribe<MyMessage>(this, "AnsData", (value) =>
            {
                string receivedData = value.Myvalue;
                Answer2.Text = receivedData;
            });
        }
        void Button3_Tapped(object sender, EventArgs e)
        {

            PopupNavigation.PushAsync(new AnswerPopup(tranzaction));

            MessagingCenter.Subscribe<MyMessage>(this, "AnsData", (value) =>
            {
                string receivedData = value.Myvalue;
                Answer3.Text = receivedData;
            });
        }

我的弹出页面

   private string selectedItem;     
        private void AnsList_Tapped(object sender, SelectedItemChangedEventArgs e)
        {
            var selectedCategory = e.SelectedItem as Answer;
            if (selectedCategory != null)
                selectedItem = selectedCategory.Text;
            MessagingCenter.Send(new MyMessage() { Myvalue = selectedItem.ToString() }, "AnsData");
            PopupNavigation.PopAsync();
        }

Answer 1

首先，您不需要多次订阅，只需每页执行一次（通常在构造函数中）

其次，向MyMessage 添加一个属性，它会告诉您调用了哪个按钮

MessagingCenter.Subscribe<MyMessage>(this, "AnsData", (value) =>
        {
            string receivedData = value.Myvalue;

            switch (value.Question) {
              case "Q1":
                Answer1.Text = receivedData;
                break;
              case "Q2":
                Answer2.Text = receivedData;
                break;
              case "Q3":
                Answer3.Text = receivedData;
                break;
            }


        });

最后，在调用AnswerPopup 时，传递问题的密钥（然后在调用MessagingCenter.Send() 时需要通过MyMessage 传递回来

void Button1_Tapped(object sender, EventArgs e)
    {
        // use "Q2", "Q3", etc as appropriate
        PopupNavigation.PushAsync(new AnswerPopup(tranzaction, "Q1"));
    }