title: ARC circular retain detection
body: <p>I ported some old code over to Objective-C ARC (Automatic Reference Counting) and it seems to work great.  Except a rather large, high-level object is not being deallocated when it is popped off of my navigation stack, making me believe I have a retain cycle somewhere that ARC has hidden from me (or at least made difficult to track down).  What is the best way to weed out this potential retain cycle and/or what is a good way to determine the cause of a memory leak under ARC?  Thanks!</p>