Xcode backtraces, symbolic breakpoints, watchpoints

Brian Hardy of the Big Nerd Ranch on Xcode debugging:

But occasionally, a hairy problem will surface that demands more finesse. Imagine, for example, that you’re debugging something that only happens every five minutes on a timer, and then triggers some multi-threaded gobbledy-gook where timing is critical to reproducing a bug.

This tutorial describes in detail several Xcode debugging techniques, including backtraces, symbolic breakpoints and watchpoints.