...It's because not every retain cycle is a leak, and we might want to filter them out. Every filter is a block that having two FBObjectiveCGraphElement objects can say, if their relation is valid. If you want to profile your app, you might want to have an abstraction over how to get candidates for FBRetainCycleDetector. While you can simply track it your own, you can also use FBAllocationTracker. It's a small tool we created that can help you track the objects.