Arrays

Arrays are collections of values that are stored as a single value. For example, John, Paul, George, and Ringo are names, but arrays let you group them in a single value called The Beatles.

In code, we write this:

let john = "John Lennon"
let paul = "Paul McCartney"
let george = "George Harrison"
let ringo = "Ringo Starr"

let beatles = [john, paul, george, ringo]

That last line makes the array: it starts and ends with brackets, with each item in the array separated by a comma.

You can read values from an array by writing a number inside brackets. Array positions count from 0, so if you want to read “Paul McCartney” you would write this:

beatles[1]

Be careful: Swift crashes if you read an item that doesn’t exist. For example, trying to read beatles[9] is a bad idea.

Note: If you’re using type annotations, arrays are written in brackets: [String], [Int], [Double], and [Bool].