问题描述
我有一个@class Foo，其中包含一个__weak id bar ivar.来自不同类的方法的几种操作可能导致对象消失，从而被bar破坏.
I have a @class Foo which contains a __weak id bar ivar. Several actions from methods in different classes can cause the object to disappear and thus get bar niled.
当ARC自动禁用ivar时，我想执行一个操作.
I want to perform an action when the ivar is automatically niled by ARC.
如果可能，我要避免将bar转换为属性或使用键值观察.
If possible, I would want to avoid turning bar into a property or using Key-Value Observing.
这甚至有可能吗?如果不是，可以将KVO用作非财产的垃圾吗?
Is this even possible? If not, can KVO be used against non-property ivars?
推荐答案
KVO无法成功用于非财产IVAR.
KVO cannot be successfully used on non-property IVARs.
当Objective-C的ARC使IVAR无效时，您将无法从运行时进行检测.
You cannot detect from the runtime when Objective-C's ARC nils an IVAR.
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