I’m not sure if XCode 4 makes this technique unnecessary. Since I originally wrote this, I’ve seen XCode 4.0.2 stop at NSAssert on its own, without me setting this breakpoint. But it may be helpful to someone somehow. So here it is:
Xcode 3: Run Menu -> “Manage Breakpoints”
XCode 4: Go to the breakpoint navigator.
Click the + button at the bottom of the navigator, select “Add Symbolic Breakpoint…” from the contextual menu that appears.
In the “Symbol” box, enter
Then click “Done”. (NOTE: this is the default assertion handler. If you are using a custom assertion handler, you probably need to specify a symbol for its object and method.)