When the iOS platform was introduced in 2007, it brought lots of exciting new features for users and drastically changed the concept of mobile devices.

Despite its huge success, it lacked some features at the time, which were considered basic. One of these features was multitasking, that is, support for running multiple processes at the same time. The platform actually did support multitasking to system processes internally, but it was not available to developers. Starting with iOS 4, Apple provided support for multitasking, although it is still quite different from what most developers are accustomed to.

In this chapter, we will discuss how to make use of the platform's multitasking features. We will see under what circumstances we can use these features and what functionality we can provide to the users of our apps through multitasking. Specifically, we will learn about an application's states and its runtime lifecycle. Through a series of detailed example projects, we will...