Exceptions in Cocoa code

The Objective-C language supports exceptions and that feature is fully supported by PyObjC: the bridge will translate between Python and Objective-C exceptions on transitions in either way between the two languages.

That said, Objective-C code in general only uses exception for serious bugs and most code, likely including Apple frameworks, are not written with exception safety in mind.

In general it is advisable to avoid raising exceptions that will cross the boundary from Python to Objective-C, for example by using a decorator that catches and logs exceptions.