使用 ARC 手动保留

发布于 2024-12-10 11:17:30 字数 311 浏览 0 评论 0原文

在 ARC 之前，我有以下代码，可以在异步操作正在进行时保留委托：

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

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

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

ARC 中的此模式等效于什么？

原文

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];
}

What is the equivalent to this pattern with ARC?

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无远思近则忧 2024-12-17 11:17:30

我偶尔需要手动保留和释放东西（有时只是为了调试），并想出了以下宏：

#define AntiARCRetain(...) void *retainedThing = (__bridge_retained void *)__VA_ARGS__; retainedThing = retainedThing
#define AntiARCRelease(...) void *retainedThing = (__bridge void *) __VA_ARGS__; id unretainedThing = (__bridge_transfer id)retainedThing; unretainedThing = nil

这通过使用 __bridge_retained 和 __bridge_transfer 将东西转换为 (void *) 来实现，这会导致东西被保留，或者创建强引用而不调用保留。

玩得开心，但要小心！

I have occasionally needed to manually retain and release things (sometimes just for debugging) and came up with the following macros:

#define AntiARCRetain(...) void *retainedThing = (__bridge_retained void *)__VA_ARGS__; retainedThing = retainedThing
#define AntiARCRelease(...) void *retainedThing = (__bridge void *) __VA_ARGS__; id unretainedThing = (__bridge_transfer id)retainedThing; unretainedThing = nil

This works by using the __bridge_retained and __bridge_transfer to cast things to and from (void *) which causes things to be retained, or to create a strong reference without calling retain.

Have fun, but be careful!

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幸福丶如此 2024-12-17 11:17:30

为什么不在异步任务期间将委托对象分配给强 ivar？

或者在 executeAsyncWork 中有一个局部变量

- (void)executeAsyncWork
{
    id localCopy = _delegate;

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

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

Or have a local variable in 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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留一抹残留的笑 2024-12-17 11:17:30

像这样的事情：

- (void)startAsyncWork
{
    id<YourProtocol> delegate = _delegate;
    dispatch_async(/* some queue */, ^{
        // do work
        [delegate doSomething];
    }
}

只要需要，该块将保留委托......

Something like this:

- (void)startAsyncWork
{
    id<YourProtocol> delegate = _delegate;
    dispatch_async(/* some queue */, ^{
        // do work
        [delegate doSomething];
    }
}

The block will retain the delegate as long as needed...

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~没有更多了~