手动保留ARC [英] Manual retain with ARC

问题描述

在ARC之前我有以下代码在异步操作正在进行时保留委托：

Before ARC I had the following code that retains the delegate while an async operation is in progress:

- (void)startAsyncWork
{
    [_delegate retain];
    // calls executeAsyncWork asynchronously
}

- (void)executeAsyncWork
{
    // when finished, calls stopAsyncWork
}

- (void)stopAsyncWork
{
    [_delegate release];
}

ARC的这种模式相当于什么？

What is the equivalent to this pattern with ARC?

推荐答案

为什么不在异步任务期间将你的委托对象分配给强大的ivar？

Why not just assign your delegate object to a strong ivar for the duration of the asynchronous task?

或者在中有一个局部变量executeAsyncWork

- (void)executeAsyncWork
{
    id localCopy = _delegate;

    if (localCopy != nil) // since this method is async, the delegate might have gone
    {
        // do work on local copy
    }
}

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