How to add a breakpoint to objc_exception_throw?
I think Brad's answer is pretty clear; hopefully this can help if you're not finding it clear.
In Xcode, from the top menu click on Run > Show > Breakpoints. A new window pops up.
Select "global breakpoints" in the left hand menu. There should be a box on the right under the "Breakpoint" column with the text "Double-Click for symbol". Single-click in this box and type in "objc_exception_throw".
Then, single-click in the space next to "objc_exception_throw" under the "location" column. A box will appear for you to type in the location (in this case, "libobjc.A.dylib"). I've made a screenshot that will hopefully help:
In Xcode 4 this great breakpoint can be added via "+" button on Breakpoints section (⌘ + 6)
in Xcode 6 -- from top menu
Debug > Breakpoints > Create Exception Breakpoint