What’s the difference between a function and a method?

Swift version: 5.0

Paul Hudson    @twostraws    May 28th 2019

Some folks use “function” and “method” interchangeably, but there’s a small difference: both of them are reusable chunks of code, but methods belong to classes, structs, and enums, whereas functions do not.

So:

func thisIsAFunction() {
}

struct Person {
    func thisIsAMethod() {
    }
}

Because methods always belong to a data type, they have a concept of self that functions do not. This is a special value passed in by Swift, and it refers to whatever instance the method was called on.

Swift uses the same keyword, func, for both functions and methods.

Available from iOS 9.0

Did this solution work for you? Please pass it on!

Tweet

Other people are reading…

• What does unowned mean?
• What are the changes in Swift 2.2?
• What is typecasting?
• How to print debug text in Swift
• How to pass the Fizz Buzz test

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.