Object-C Strong and Weak

leearnold

于 2012-03-05 21:34:12 发布

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分类专栏： Mac iOS

本文链接：https://blog.youkuaiyun.com/leearnold/article/details/84163501

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本文探讨了内存管理中强引用与弱引用的区别。强引用确保对象存活直到明确设置为nil，而弱引用则依赖其他强引用的存在来保持对象不被释放。文章还介绍了dealloc方法的作用，即当对象即将从内存中移除时调用。

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strong vs weak

strong “keep this in the heap until I don’t point to it anymore” I won’t point to it anymore if I set my pointer to it to nil.Or if I myself am removed from the heap because no one strongly points to me!
weak “keep this as long as someone else points to it strongly” If it gets thrown out of the heap, set my pointer to it to nil automatically (if user on iOS 5 only).
This is not garbage collection! It’s way better. It’s reference counting done automatically for you.
Finding out that you are about to leave the heap A special method, dealloc, is called on you when your instance’s memory is freed from the heap. You will rarely ever have to implement this method. It’s “too late” to do much useful here.

- (void)dealloc
{
        [[NSNotificationCenter defaultCenter] removeObserver:self]; 
}