Intercept all messages to an objc object for debugging goodness

Logging all Objective-C messages is noisy. Using dtrace lets you catch particular messages, but is hard (and Mac only). If you want to see how a particular object is being used, drop in a debug proxy and use Xcode's debugger actions to log, make sounds or do other things when the proxy is messaged.

http://blog.securemacprogramming.com/2012/04/the-debugger-of-royalty/