Is there an easy way of finding out where a Cocoa exception, such as "*** -[NSCFDictionary setObject:forKey:]: attempt to insert nil value", originates from? By where I mean which method in my own code made the offending call to NSCFDictionary. I'm not even sure if this is really an exception or if it's just an error log. Is it possible to make a conditional breakpoint in methods that are in the imported frameworks? Or can I create a proxy method to catch calls and then forward them, so that I can put up a breakpoint in the proxy method instead?