android - 泄漏在 xaml 中加载的自定义 View

Question

我的一个 Activity 从未被处置，因为它的一个 subview 注册到事件处理程序并且从不注销它，我试图在 subview Dispose 方法中注销它但它从未被调用。

subview 使用事件处理程序 CrossConnectivity 在网络连接断开时显示自身，并在连接再次接通时隐藏自身。

此 subview 在布局 axml 中引用，因此在布局展开时对其进行实例化。

只加载布局的 Activity

using Android.App;
using Android.OS;

namespace MyNamespace
{
    [Activity(Label = "SimpleActivity")]
    public class SimpleActivity : Activity
    {
        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
            SetContentView(Resource.Layout.SimpleLayout);
        }
    }
}

上述布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

        <MyNamespace.NetworkStateView
        android:text="No network"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/textViewNetworkState" />
</LinearLayout>

自定义 View

using System;
using Android.Content;
using Android.Util;
using Android.Views;
using Android.Widget;
using Connectivity.Plugin;
using Connectivity.Plugin.Abstractions;

namespace MyNamespace
{
    public class NetworkStateView : TextView
    {
        public NetworkStateView(Context ctx) : base(ctx)
        {
        }

        public NetworkStateView(IntPtr javaReference, Android.Runtime.JniHandleOwnership transfer) : base(javaReference, transfer)
        {
        }

        public NetworkStateView(Context context, IAttributeSet attrs) : base(context, attrs)
        {
        }

        protected override void OnFinishInflate()
        {
            base.OnFinishInflate();
            BindConnectivity();
        }

        void BindConnectivity()
        {
            CrossConnectivity.Current.ConnectivityChanged += OnConnectivityChanged;
            UpdateVisibility();
        }

        void OnConnectivityChanged(object sender, ConnectivityChangedEventArgs e)
        {
            UpdateVisibility();
        }

        void UpdateVisibility()
        {
            Visibility = CrossConnectivity.Current.IsConnected ? ViewStates.Gone : ViewStates.Visible;
        }

        protected override void Dispose(bool disposing)
        {
            CrossConnectivity.Current.ConnectivityChanged -= OnConnectivityChanged;
            base.Dispose(disposing);
        }
    }
}

Answer 1

终于在写题的时候找到了解决方法，我重写了OnDetachedFromWindow，去掉了里面的事件处理程序

protected override void OnDetachedFromWindow()
{
    base.OnDetachedFromWindow();
    CrossConnectivity.Current.ConnectivityChanged -= OnConnectivityChanged;
}