WITHIN A SHORT TIME SPAN OF SIX MONTHS, Apple revised the iPhone OS twice. The first time was in January 2010, when Apple announced a magical and revolutionary product: the iPad. Because the iPad is a tablet computer that is based on the iPhone OS, this meant that there were instantly more than 250,000 applications that could run on the iPad. Then, in April Apple announced (and subsequently shipped in June) the next major release of the iPhone OS — 4.0. Apple also took this opportunity to rename this new release of the OS, calling it iOS. This signifies Apple's grand plan to run the iPhone OS on a wide variety of devices, not just on phones. Included with the new release of the OS is a new SDK, the iPhone SDK 4, which enables developers to take advantage of the various features provided by the operating system — key of which is the capability to run background applications.
When I first started learning about iPhone and iPad development, I went through the same journey that most developers go through: Write a Hello World application, play around with Interface Builder, try to understand what the code is doing, and repeat that process. I was also overwhelmed by the concept of a View Controller, and wondered why it was needed if I simply wanted to display a view. My background in developing for Windows Mobile and Android did not help much, and I had to start working with this concept from scratch.
This book was written to help jumpstart beginning iPhone and iPad developers. ...