Functions

When I first learned to program with BASIC, my first few programs were written in one long block of code. I quickly realized that I was repeating the same code over and over. I thought that there must be a better way to do this, which was when I learned about subroutines and functions. Functions are one of the key concepts that you need to understand to write good code.

In this chapter, we will cover the following topics:

• What are functions?
• How to return values from a function
• How to use parameters in a function
• What are variadic parameters?
• What are inout parameters?

In Swift, a function is a self-contained block of code that performs a specific task. Functions are generally used to logically break our code into reusable named blocks. The function's name is used to call the function.

When we define a function, we can also optionally define one or more parameters. Parameters are named values that are passed into...