CODEWITHSUNDEEP
iosobjective-cautomatic-ref-countinginstruments
Drew
Drew

Reputation: 8963

Debugging strategies for over-retain in ARC?

I've got some objects that are passed to a lot of different views and controllers in my application. They're not getting deallocated when I expect them to. Obviously there is an errant strong pointer somewhere, but the surface area of where it could be is very large--these objects are moved into and out of a lot of different data structures.

My usual go-to solution here is Leaks (which reports no cycles) and Allocations (which lists 500+ retain/releases for this object). Is there any way to reduce my search space here?

Ideally there would be a tool that would let me type in a pointer and see all the strong references to the object, and I could probably eyeball the list and find the extra reference in about 60 seconds. In fact, there is such a tool -- the Object Graph instrument -- but it's not available for iOS software.

Upvotes: 8

Views: 3148

Answers (2)

Anshad Rasheed
Anshad Rasheed

Reputation: 2566

The simplest method to identify whether there is retain cycle or not by just putting a breakpoint in your controller's dealloc()/deinit()(swift) method and whenever you pop your controller check this methods getting called or not if there is retain cycle present in your controller this methods won't get called.

Swift

deinit {
    print("Memory to be released soon")
}

Objective C

- (void)dealloc {

    NSlog("Memory to be released soon");

}

If you want to get more details about the strong references and root causes you should go with Instrument as the other answer.

Upvotes: 0

David Doyle
David Doyle

Reputation: 1716

You want the Allocations instrument. To track an individual object type, start the application. You need to create a heapshot at every significant event (I usually create them at points when you've just transitioned to or from a view controller).

Once you've got a heapshot that should have the object you're interested in tracking down, then you should be able to find that object type under the heapshot's disclosure triangle. For each object of that type, you can get a history of what retains and releases have been sent to that object by clicking on the arrow in that object's row.

Upvotes: 19

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