The fact that he chose the fake method name performAction:withTwoParameters: betrays that he doesn't know what he's talking about. Under the Apple style guide you would describe the parameters next to the arguments in the method signature itself, and in this case would use something more like performActionWithParameter1:parameter2.

You do this so that you actually know what you're putting into the damn function. As soon as you've typed 'object per' Xcode's autocomplete will have filled out the rest of the entire function, complete with parameter descriptions and little empty bubbles with the expected argument class for you to tab over and type your arguments into. This is indispensable if you have a method with a large number of arguments.