Watching messages to an object in Xcode debugger

Question

I'd like to use gdb or Xcode's debugger to watch every message sent to an object in an Objective-C 2.0 program. I don't care about arguments and such, as I just need to see every message it receives (retain, release, autorelease, etc). I also don't want to profile my entire program.

Is there a means, in Xcode, to select an instance (possibly by address) and say "show me every message sent to this object"? Since the plumbing is fairly standard, I imagine there would have to be a probe hook or something. Anyone ever done this?

(Aside from subclassing the object in question, of course; looking for a more general solution.)

This is for iPhone development with Xcode 3.2 on Snow Leopard.

Answer 1

You can set the NSObjCMessageLoggingEnabled environment variable to YES and then grep/filter through the resulting log for the object you're interested in.

Here's a relevant blog post as well, though I'm not sure how much of the information there is still true in the runtime today. (It might all be. I really don't know.)