[mikeash]

I'd argue that this would be a bug. B has a weak reference to A here (whether explicitly or just implicitly through KVO) and that weak reference should be cleared out first thing before tearing down the rest of the object. The method should start with a [myB setA: nil], then go on with the rest. Setting that to nil would then remove the observation, solving the problem.

There may well be similar setups which aren't broken which still exhibit the problem, though.

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