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I am debugging the my Cocoa application and noticed using the Instruments.app allocation profile that the model object graph is not deallocating as I expect. Basically when I remove a root model object from the my NSDocument I was expecting the whole object graph for that object to be deallocated. That doesn't happen, which means that there is a strong reference to my root model object somewhere else in the application.

Is it possible to get a list of object which have a reference to a specific object in Cocoa either programmatically or using Instruments.app? If I could know where the strong reference is held this would help with debugging this problem.

I found this similar question, How to get the reference count of an NSObject?, but this simply says which how many references there are, not which objects hold the references.

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Daniel Farrell
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Not in this way. The only information that is stored inside of a running process is the number of retains on an object (number of times "retain" has been called net the number of times "release" has been called). This is not the same as the number of references (number of "strong" pointers to the memory). Most memory locations do not have a side table of things that point to them in Cocoa.

In Instruments, you can turn on "record reference counts" and see everywhere the retain count is increased or decreased. See Instruments Allocations track alloc and dealloc of objects of user defined classes for a good explanation of how to do that. This won't tell you where you've made your mistake, but it will tell you where the retains are occurring.

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Rob Napier
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