If you don't understand the title of this post, don't bother reading any further. If you do, here's a nice regular expression that will, given an Obj-C source file (.h or .m), give you all of the method signatures. It should work in every case that I can think of, but if you're doing anything involving weird types or preprocessor macros it should work.

(\-|\+)\s*\([\w\s]+(\s*\*)?\)\w+(:\([\w\s]+(\s*\*)?\)\w+\s?)?(\w+:\([\w\s]+(\s*\*)?\)\w+\s?)*