Memory_Management

Dealloc

Last week there was a bit of a Twitter in-fight in the iOS community over the “right” way to release your instance variables in dealloc. I think Rob actually started it, to be honest, but I probably shouldn’t be bringing that up.

Basically, several developers were claiming that there’s never a reason to set an instance variable to nil in dealloc, while others were arguing that you should always do so.

To me, there didn’t seem to be a clear and compelling winner between the two approaches. I’ve used both in my career. However, since we’re in the process of trying to decide which approach to use in the next edition of Beginning iPhone Development, I reached out to Apple’s Developer Tools Evangelist, Michael Jurewitz, to see if there was an official or recommended approach to handling instance variables in dealloc.

Other than the fact that you should never, ever use mutators in dealloc (or init, for that matter), Apple does not have an official recommendation on the subject.

However, Michael and Matt Drance of Bookhouse Software and a former Evangelist himself, had discussed this issue extensively last week. They kindly shared their conclusions with me and said it was okay for me to turn it into a blog post. So, here it is. Hopefully, I’ve captured everything correctly.

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