如何以Xamarin形式使用消息传递中心 [英] How to use Messaging center in xamarin forms

问题描述

我正在尝试使用消息中心而不是xamarin形式的Messenger，我对消息中心一无所知，我曾尝试使用Bellow代码以xamarin形式进行订阅和发送消息

I am trying to use messaging center instead of Messenger in xamarin forms I have no idea about messaging center I tried Bellow code to subscribe and Send Message in xamarin forms

MessagingCenter.Send(this, "TodoTable", "Todo");

但是我不知道从哪里可以订阅以下消息，我尝试了下面的代码:

But I have not Idea from where I can subscribe to this message I tried bellow code :

MessagingCenter.Subscribe<TodoClass>(this, Todo, async (sender, arg) =>
{
  await RefreshCommand.ExecuteAsync();
});

这给我带来了错误任何帮助将不胜感激:)

This is giving me error Any Help will appreciated :)

推荐答案

要改善@ user2825546的答案，如果您只希望订阅来自视图模型的消息，则在发送讯息:

To improve the answer by @user2825546, if you wish to subscribe to only messages from your view-models, you need to specify the base class type when sending the message:

MessagingCenter.Subscribe<BaseViewModel, string>(this, "ShowError", (view, message) => { });

public class StartupViewModel : BaseViewModel
{
     //Like this...
     MessagingCenter.Send<BaseViewModel, string>(this, "ShowError", "Message");
     //Or...
     MessagingCenter.Send((BaseViewModel)this, "ShowError", "Message");
}

---

在测试时，我尝试以StartupViewModel的形式发送消息，但是侦听器未收到消息.我猜想是这样，因为该类是从BaseViewModel派生的.

---

When testing, I tried to send the message as StartupViewModel, but the listener was not receiving the messages. I guessed that it would, since the class derives from the BaseViewModel.

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