As your programs become more complex, you will use extensions (covered in Chapter 8, Protocols, Extensions, and Error Handling) to organize your code. Extensions can help you to make code more legible and avoid clutter. They also enable you to extend the functionality of a class.

You will update four classes: ExploreViewController, RestaurantListViewController, LocationViewController, and MapViewController. You will segregate blocks of related code using extensions. Let's begin with ExploreViewController in the next section.