On Jul 17, 2014, at 11:01 PM, Jens Alfke <[email protected]> wrote:
> Every once in a while I run into a bug in my code that’s triggered by self
> getting dealloced in the middle of a method. It’s usually something like
> - (void) someMethod {
> doSomeStuff;
> [self.delegate object: self didSomeStuff: yeah];
> doSomeMoreStuff;
> }
> where it turns out that the delegate method clears its reference to me, and
> that was the last reference, causing self to get dealloced during the
> delegate call, causing doSomeMoreStuff to crash.
>
> Once I’ve identified such a bug, the fix is easy: put a [[self retain]
> autorelease] at the top of the method. Except now I’m using ARC, and I can’t
> find a simple way of doing it. I tried adding
> __unused id retainedSelf = self;
[Conjecture] I haven’t tried it, but maybe the following would work:
__unused id retainedSelf __attribute__((objc_precise_lifetime)) = self;
Now retainedSelf should be retained until it goes out of scope. But I don’t
know whether the optimizer is still allowed to mess with this.
> but the optimizer recognizes that retainedSelf isn’t used and strips it out,
> making this a no-op. The only thing I’ve found that works is
> CFRetain((__bridge CFTypeRef)self);
> at the top of the method, and a corresponding CFRelease at the end, but this
> is pretty ugly and could cause leaks if the method returns early.
>
> Am I missing some convenient way of doing this? I looked through the ARC
> docs, at least those I could find, and didn’t see anything relating to this.
>
> —Jens_______________________________________________
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