I thought I took pretty good notes at the WWDC but, as usual, what made sense when I wrote it didn't make sense when I read it. Actually it did make sense, but it wasn't anywhere near complete enough. Note to self: take longer better notes next time.

One of my Cocoa apps was (recently) crashing in obc-msgSend. Upon seeing this, I was delighted to remember a specific bit of one of the developer sessions which talked precisely about this. I gleefully turned to my notes and sure enough, learned that crashes in obc-msgSend are a sign of prematurely deallocated objects, and I should set MSZombieEnabled [sic] to find them. Sadly, I neglected to expand on the "MSZombieEnabled" thing or, in fact, spell it correctly.

Happily, thanks to the power of Google, I found what I needed in this wonderfully complete article on, you guessed it, debugging retain counts (complete with where to set NSZombieEnabled):

Big Nerd Ranch Weblog >> Debugging retain counts