如何确定我是否有指针释放对象？ [英] How to determine if I have a pointer to released object?

问题描述

在一个函数中，我正在处理一个可能被破坏的对象，在运行时，我可以以某种方式确定我的对象是否被破坏？

In a function I am processing an object which may be corrupted sometimes, at runtime, can I somehow determine whether or not my object is corrupted?

推荐答案

真正做到这一点的唯一方法是利用ARC（和iOS 5，在此之前不起作用）利用一个新的东西称为 __ weak 指针

The only way to really do this is to leverage a new thing with ARC (and iOS 5, doesn't work before this) called __weak pointers.

根据定义，还应注意 __ weak 变量不保留。如果 __ weak 变量保留它的目标，那么根据定义，它不能自己释放。

It should also be noted that __weak variables do not retain, by definition. If a __weak variable retained it's target, then by definition, it couldn't release itself.

基本上， __ weak 指针是一个变量，当它被释放时，它自动设置为 NULL 。因此，您可以执行此操作来确定对象是否被取消分配：

Basically, a __weak pointer is a variable that automatically set's itself to NULL when it is deallocated. Thus, you can do something like this to determine if an object is deallocated:

__strong id object; // required so that the object doesn't get deallocated right away
__weak id _weakRef;

object = [NSObject new];
_weakRef = object;

// do stuff with 'object'

if (_weakRef)
{
    // 'object' hasn't been deallocated yet, do something with it.
}

通常来说，你不会坚持强弱弱的参考对象，但是，因为这导致 _weakRef 无用（只需检查你设置对象到

Normally speaking, you don't hold onto a strong and weak reference to an object, however, as this causes _weakRef to be useless (just check when you set object to nil).

我也会警惕，只能设计一个基于 __ weak 变量，特别是如果你正在制作一个框架。没有什么说烦人就像使用iOS 5作为目标部署。

I would also caution against having a design pattern based solely on __weak variables, especially if you are making a framework. Nothing says 'Annoying' like having to use iOS 5 as your target deployment.

我希望这篇文章能帮助您更深入地了解弱引用如何工作，如果不是有一个很好的维基百科文章，您可以在这里阅读：

I hope this post helped you get a deeper understanding of how weak references work, and if not, there is an excellent wikipedia article you can read here:

http： /en.wikipedia.org/wiki/Weak_reference

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