Why would you use an ivar?
I usually see this question asked the other way, such as Must every ivar be a property? (and I like bbum's answer to this Q). I use properties almost exclusively in my code. Every so often, however, I work with a contractor who has been developing on iOS for a long time and is a traditional game programmer. He writes code that declares almost no properties whatsoever and leans on ivars. I assume he does this because 1.) he's used to it since properties didn't always exist until Objective C 2.0 (Oct '07) and 2.) for the minimal performance gain of not going through a getter / setter. While he