Nowadays, multitasking is something very common; an application can do lots of things at the same time. If we have a multicore processor such as an iPhone 4S or newer, or an iPad 2 or newer, you can even improve the performance. Of course, you shouldn't use the multitasking feature for everything, because commuting from one task to another countlessly can harm the performance.

In this chapter, we will learn different types of multitasking and when you should use each of them. First, we will start with threads, then we will see NSOperations, and at last, we will look at ways to use GCD.