I have long been a fan of Test Driven Development (TDD). I have used all kinds of frameworks for doing my tests and for all of them have adopted the Act, Arrange, Assert pattern. I have looked into doing Behaviour-Driven Development and like the idea, just never found a framework that I was comfortable with and could use back and forth with unit testing.
I have been using OCUnit that ships with Xcode to do my testing. I decided that I wanted to branch out. I had heard good things about Kiwi for doing BDD with iOS. I decided that I should try it out. I normally I stick to the web and spelunking, yet this time I decided to buy a book on the subject: Test Driving iOS Development with Kiwi. This book is only available from the iBooks store.
I have to say the book was worth every penny. I really thought it was a simple and easy introduction. It doesn't try and cover every nook of the framework, but it gives you enough information to get you started and how you can easily use it. It also takes advantage of the fact it works on the iPad: you get media built right into the book. Rather than just text walk throughs, you get video / slides of how to do things visually. I really love this new way of doing books.
If you have never done or looking to do testing for you application (shame on you if you don't), you should really look into this book and Kiwi. I give it 5 stars!