In addition to the basic UIKit and Foundation frameworks, which supply the fundamental interface and utility classes for all apps, Cocoa supplies numerous optional frameworks that you can use if your app has special needs. This part of the book introduces some of these frameworks and their related topics. At the same time, it necessarily exercises some restraint. To explore all of the additional iOS frameworks in full depth would more than double the size of this book! So this part of the book fully explains the basics, but then stops and leaves you to go further on your own if you need to; it teaches you what you need to know to get started, and it trains you to understand and explore these and related frameworks independently if your app requires a further level of depth and detail.