This chapter has taught you how to harness the powers given to you by UICollectionView and UICollectionViewLayout in your apps. You saw that collection view come with a nice grid layout out of the box and that you can easily customize this grid layout by implementing a couple of delegate methods. Next, you created your layout to make your contacts app look more interesting and engaging. You also learned about the collection view's performance characteristics and how to implement great features such as contact selection, deletion, and reordering.

You have learned some fairly complex matter in this chapter, and you have implemented some pretty advanced features, such as your custom layout, gesture recognition, and using animations to provide feedback to users. All of these techniques are important parts of your toolbox as an iOS developer because they are applicable...