This style guide outlines the coding conventions that I try to stick to when writing Objective-C. I'm posting it here mostly as a brain dump and easy reference for the future, and to formalise it a little more.
It's pretty similar to that of the NYTimes. This document is mostly a customised version of that, you should go check theirs out!
If you're looking to see some of the reasons behind some choices, or for something I haven't covered, look at the sites below, Apples documentation is pretty great.