Luke Cunningham (@icaruswings) and I presented a talk at the June 2011 Cocoaheads meet up titled "Epic refactorings and patterns to make your code awesome!".
The topic was inspired by a number of design patterns we employed while developing the new realestate.com.au iPad application. We highlighted some of shortcomings we found with UIViewController and demonstrated our end result - ViewCoordinator
The book highlighted in the presentation is Agile Software Development. Principles, Patterns, and Practices by Bob Martin. The two design patterns we highlight form the book were single responsibility and Interface segregation.
The slides are available on Slide Share.
Note: the video's audio is quite average.