Head First Swift

Chapter 4. Functions and Enums: Reusing Code on Demand

Functions in Swift allow you to package up a specific behavior or unit of work into a single block of code that you can call from other parts of your program. Functions can be standalone, or they can be defined as part of a class, a structure, or an enumeration, where they are usually referred to as methods. Functions let you break down complex tasks into smaller, more manageable, and more testable units. They’re a core part of the way you structure a program with Swift.

Functions in Swift let you reuse code

Like many programming languages, Swift has a feature known as functions. Functions let you package up some code, and reuse it if you need to run it more than once.

We’ve been using functions a fair bit already: the print function, for example, is a built-in function that lets us print things for display. Swift has lots of other built-in functions, and you’ll get a chance to use some of them in a moment.

What can functions do?

Functions can, in no particular order, do all sorts of things, including:

Note

Including, but not limited to!

• Be defined as a block of code that just does something, and doesn’t need any ...