BLACK FRIDAY SALE: Save big on all my Swift books and bundles! >>

Creating empty collections

Arrays, sets, and dictionaries are called collections, because they collect values together in one place.

If you want to create an empty collection just write its type followed by opening and closing parentheses. For example, we can create an empty dictionary with strings for keys and values like this:

var teams = [String: String]()

We can then add entries later on, like this:

teams["Paul"] = "Red"

Similarly, you can create an empty array to store integers like this:

var results = [Int]()

The exception is creating an empty set, which is done differently:

var words = Set<String>()
var numbers = Set<Int>()

This is because Swift has special syntax only for dictionaries and arrays; other types must use angle bracket syntax like sets.

If you wanted, you could create arrays and dictionaries with similar syntax:

var scores = Dictionary<String, Int>()
var results = Array<Int>()
Hacking with Swift is sponsored by RevenueCat

SPONSORED In-app subscriptions are a pain to implement, hard to test, and full of edge cases. RevenueCat makes it straightforward and reliable so you can get back to building your app. Oh, and it's free if your app makes less than $10k/mo.

Learn more

Sponsor Hacking with Swift and reach the world's largest Swift community!

BUY OUR BOOKS
Buy Pro Swift Buy Pro SwiftUI Buy Swift Design Patterns Buy Testing Swift Buy Hacking with iOS Buy Swift Coding Challenges Buy Swift on Sundays Volume One Buy Server-Side Swift Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Advanced iOS Volume Three Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with macOS Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let us know!

Average rating: 4.6/5

 
Unknown user

You are not logged in

Log in or create account
 

Link copied to your pasteboard.