Grand Central Dispatch, Over and Out

This has been a pretty heavy chapter, with a lot of new concepts thrown your way. Not only have you learned about a complete new feature set Apple added to the C language, but you've also discovered a new conceptual paradigm for dealing with concurrency without worrying about threads. We also demonstrated some techniques for making sure your apps play nicely in the multitasking world of iOS. Now that we've gotten some of this heavy stuff out of the way, let's move on to the next chapter, which focuses on drawing. Pencils out, let's draw!