ARC的手动对象生存期 [英] Manual object lifetime with ARC

问题描述

检查以下代码，并假设它是在ARC下编译的:

Examine the following code, and assume it was compiled under ARC:

- (void)foo {
    NSOperationQueue *oq = [[NSOperationQueue alloc] init];
    [oq addOperationWithBlock:^{
        // Pretend that we have a long-running operation here.
    }];
}

尽管将操作队列声明为局部变量，但只要其具有正在运行的操作，其生存期就会超出该方法的范围.

Although the operation queue is declared as a local variable, its lifetime continues beyond the scope of the method as long as it has running operations.

这是如何实现的?

更新:

我感谢罗伯·梅诺夫(Rob Mayoff)的深思熟虑的评论，但我认为我没有正确提出问题.我不是在问关于NSOperationQueue的特定问题，而是在问关于ARC对象寿命的一般问题.具体来说，我的问题是这样的:

I appreciate Rob Mayoff's well-thought-out comments, but I think I did not ask my question correctly. I am not asking a specific question about NSOperationQueue, but rather a general question about object lifetime in ARC. Specifically, my question is this:

在ARC下，对象如何才能参与其自身生命周期的管理?

我从事程序员已经很长时间了，并且我很清楚这种事情的陷阱.我不希望就这是一个好主意还是不好的主意进行演讲.我认为总的来说这是一个不好的选择.相反，我的问题是学术性的:这是一个好主意还是不好的主意，人们将如何在ARC中做到这一点?这样做的具体语法是什么?

I've been a programmer for a very long time, and I'm well aware of the pitfalls of such a thing. I am not looking to be lectured as to whether this is a good or bad idea. I think in general it is a bad one. Rather, my question is academic: Whether it's a good or bad idea or not, how would one do this in ARC and what is the specific syntax to do so?

推荐答案

一般而言，您可以保留对自己的引用.例如:

As a general case you can keep a reference to yourself. E.g.:

@implementation MasterOfMyOwnDestiny
{
   MasterOfMyOwnDestiny *alsoMe;
}

- (void) lifeIsGood
{
    alsoMe = self;
}

- (void) woeIsMe
{
    alsoMe = nil;
}

...

@end

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