Welcome back. Congratulations on making it to this point! So far, you have covered all the fundamental elements of the Objective-C platform. But guess what? You haven’t reached the finish line just yet! That’s because Objective-C has a variety of additional, advanced features that, once mastered, will enable you to take your programming to the next level. In Part 4 of this book, you will explore several of these features and learn how to use them in your programs.