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objective-cxcodememory-leaksinstrumentsnszombie

How to demonstrate memory leak and zombie objects in Xcode Instruments?

I would like to demonstrate memory leak and zombie object in Xcode Instruments on a class. I've found it pretty hard to trigger on purpose, especially with ARC turned on. Do you know how could I create them?

Solution

  • For A leak:

    Create two classes, A and B. A should have an @property that strongly references an instance of B. B should have an @property that strongly references an instance of A.

    A *a = [A new];
B *b = [B new];
a.b = b;
b.a = a;

    That'll create a leak.

    For a Zombie

    Create a @property that is of type assign (or a variable of type __unsafe_unretained. Then:

    A *a = [A new];
A.dangerDanger = [NSObject new];

    That should create a zombie situation; a dangling pointer, more specifically.