c# - 取消订阅 observableCollection 中的事件

Question

假设我有一个 observableCollection 类:

CustomClassName testClass = new CustomClassName();
ObservableCollection<CustomClassName> collection = new ObservableCollection<CustomClassName>();
testClass.SomeEvent += OnSomeEvent;
collection.add(testClass);

当我要从集合中删除项目时，我需要手动取消订阅事件 (OnSomeEvent) 还是应该留给 GC？退订的最佳方式是什么？

Answer 1

如果您希望收集您的元素，那么是的，您需要取消订阅。

通常的做法是:

collection.CollectionChanged += new System.Collections.Specialized.NotifyCollectionChangedEventHandler(collection_CollectionChanged);

// ...
// and add the method
void collection_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
{
    if (e.Action == System.Collections.Specialized.NotifyCollectionChangedAction.Remove)
    {
        foreach (var it in e.OldItems) {
            var custclass = it as CustomClassName;
            if (custclass != null) custclass.SomeEvent -= OnSomeEvent;
        }
    }
}