如何在Xamarin表单中实现基于当前页面的消息广播

// 消息广播器类
public class MessageBroadcaster
{
    private static MessageBroadcaster instance;
    public static MessageBroadcaster Instance
    {
        get
        {
            if (instance == null)
                instance = new MessageBroadcaster();
            return instance;
        }
    }

    public event Action<string> MessageReceived;

    public void PublishMessage(string message)
    {
        MessageReceived?.Invoke(message);
    }
}

// 接收消息的页面
public class MyPage : ContentPage
{
    public MyPage()
    {
        // 订阅消息广播器的事件
        MessageBroadcaster.Instance.MessageReceived += OnMessageReceived;
    }

    private void OnMessageReceived(string message)
    {
        // 处理接收到的消息
        // ...
    }

    protected override void OnDisappearing()
    {
        base.OnDisappearing();
        // 在页面销毁时取消订阅
        MessageBroadcaster.Instance.MessageReceived -= OnMessageReceived;
    }
}

// 发送消息的页面
public class AnotherPage : ContentPage
{
    private void SendMessage()
    {
        // 获取消息广播器的实例并发布消息
        MessageBroadcaster.Instance.PublishMessage("Hello, Xamarin Forms!");
    }
}