This book is the official companion text for the popular iTunes U series with the same name from Stanford University taught by Paul Hegarty in Fall Quarter 2013-14.
This book assumes that you are an experienced developer who is new to iOS and to Objective-C.
The first three chapters present the foundational concepts you need. The next three chapters get you up and running with your first project. Chapters 7-10 focus on ways in which we communicate among objects in an iOS application. The book wraps up with four chapters that cover some of the odds and ends presented in the iTunes U course.
Note that the book examples and descriptions are designed for Xcode 5 and iOS 7 using modern Objective-C. All of the concepts remain relevant, but improvements to Xcode 6 and iOS 8 bring alternate techniques for accomplishing some of the same results.