Skip to content

Instantly share code, notes, and snippets.

@BigZaphod
Created July 23, 2011 20:44
Show Gist options
  • Save BigZaphod/1101862 to your computer and use it in GitHub Desktop.
Save BigZaphod/1101862 to your computer and use it in GitHub Desktop.
// say that the object which is our _delegate is the only object retaining us
// and it calls this -processStuff method…
- (void)processStuff
{
// and then this happens:
[_delegate finishedSomething:self];
// now, in _delegate's -finishedSomething: it ends up releasing us like so:
// [_processorOfStuff release];
// if that delegate object was the only owner, do we get destroyed now?
// prior to ARC and assuming we're not in an autorelease pool, I think yes.
// so what happens when the -finishedSomething: method is done and we
// come back here and attempt:
[self doSomeFollowupStuff];
// do we crash and burn here? prior to ARC, the answer should be be yes
// if we're not in an autorelease pool, etc.
// so the fixes I would normally consider would be, if I could anticipate
// my delegate might trash me, I could put a [self retain]/[self autorelease]
// in our implementation of -processStuff here, or I might do a
// [_processorOfStuff autorelease] instead of release in _delegate's
// -finishedSomething: method to avoid the trouble.
// what is the best practice solution for this situation?
// it seems unreasonable to be able to perfectly anticipate what's going
// to happen to us while calling out to a delegate we might not control
// so guarding such calls with a [self retain]/[self autorelease] seemed
// okay but ARC bans the use of retain/release/autorelease, so does ARC
// solve this for us somehow (maybe by ensuring we don't die while executing
// a method) or is there something I'm missing?
}
@sjmadsen
Copy link

I ran into this exact problem where I want to keep a reference to self alive for a bit longer than ARC thinks it needs to. I didn't try putting a local variable into the function because my pattern is that a UIAlertView is shown and I need to delay the release until the user taps one of the buttons.

Adding a new instance variable to the class and assigning self to it, then nil'ing it out later is sufficient to outsmart ARC.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment