CODEWITHSUNDEEP
iosswiftxcode-storyboard
Tron Thomas
Tron Thomas

Reputation: 871

Detecting references for a Swift object allocated by a storyboard

I am developing a game for iOS using Swift. The game is played in rounds, and when a round is over, it is no longer needed. So unlike conventional applications where a storyboard scene may stick around when someone navigates away from it, I want the scene for the round to be destroyed when the game navigates to the scene following the round.

I am pretty confident I have figured out a way to do this because I’m instantiating certain objects in the scene and I have verified that the deinit method for these objects gets call when the round ends and navigation to the next scene occurs. The problem is that for one of the objects, the deinit method is not being called, and I have not been able to figure out why. The storyboard scene should be the only thing referencing the object, and searching through to source code has not revealed any other usages. It seems like something beside the storyboard scene somehow has a reference to the object and keeps it alive when the scene goes away.

I have verified the object is being created by setting a breakpoint in its init method, and that breakpoint gets hit when starting the round.

I’ve tried using the Allocations instrument to track what might be referencing the object. However when I run the game and finish the round. I can find no evidence that the Allocation instrument ever saw the object at all. I suspect the instrument may not track objects that are created by a storyboard scene, especially since I can not find traces of the other storyboard objects that do get deleted with the storyboard.

What can be done to determine why this object seems to survive past the lifetime of the storyboard scene that should own it?

Upvotes: 0

Views: 329

Answers (1)

Tron Thomas
Tron Thomas

Reputation: 871

I think found out why the object was not being destroyed. In it's initializer it was applying a closure to something else. The closure contained a reference to a member of the object, and so I think the closure was capturing self strongly even though self was never explicitly needed for things to compile successfully. This might be a bug with the Swift compiler; it could have emitted a warning or error about this; it would have been easier the find and/or prevent the problem. Anyway I changed the closure so that it captures the object's member as unowned and now the object appears to get destroyed.

Upvotes: 0

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