how to create a category class in Cocoa objective-c

Question

I'm creating an iPhone app that needs to add a custom category to extend uinavigationbar. Can anyone give me a code example of how I would create and implement this category to extend this class?

Answer 1

Here's what Wikipedia has in the way of categories (with samples) in Objective-C. It is a pretty useful tutorial on the subject.

Answer 2

The Categories and Extensions chapter of the Objective-C Programming Guide is the definitive reference.