FREE TRIAL: Accelerate your app development career with Hacking with Swift+! >>

What is a computed property?

Swift version: 5.4

Paul Hudson    @twostraws   

Swift offers us two kinds of property: a stored property is one that saves a value for use later, and a computed property is one that runs some code in order to calculate the value.

As comparison, here’s a Person struct with four stored properties and one computed one. The computed property returns a string based on joining the four stored properties into a sentence.

struct Person {
    var name = "Taylor"
    var favoriteColor = "red"
    var favoriteCity = "Tokyo"
    var favoriteFood = "tea"

    var greeting: String {
        return "Hello, my name is \(name), and I like \(favoriteFood), \(favoriteCity), and the color \(favoriteColor)."
    }
}

Note: Unlike stored properties, Swift requires you to use an explicit type with your computed properties.

Hacking with Swift is sponsored by Essential Developer

SPONSORED Join a FREE crash course for iOS devs who want to become complete senior developers — from October 18th to 24th. Learn how to apply iOS app architecture patterns through a series of lectures and practical coding sessions.

Learn more

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

Available from iOS 8.0

Similar solutions…

About the Swift Knowledge Base

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

BUY OUR BOOKS
Buy Pro Swift 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 (Vapor Edition) 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 Server-Side Swift (Kitura Edition) Buy Beyond Code

Was this page useful? Let us know!

Average rating: 4.4/5

 
Unknown user

You are not logged in

Log in or create account
 

Link copied to your pasteboard.