NEW: Learn to build amazing SwiftUI apps for macOS with my new book! >>

How does Swift let us compare many types of data?

Paul Hudson    @twostraws   

Updated for Xcode 13.3

Swift lets us compare many kinds of values out of the box, which means we can check a variety of values for equality and comparison. For example, if we had values such as these:

let firstName = "Paul"
let secondName = "Sophie"

let firstAge = 40
let secondAge = 10

Then we could compare them in various ways:

print(firstName == secondName)
print(firstName != secondName)
print(firstName < secondName)
print(firstName >= secondName)

print(firstAge == secondAge)
print(firstAge != secondAge)
print(firstAge < secondAge)
print(firstAge >= secondAge)

Behind the scenes, Swift implements this in a remarkably clever way that actually allows it to compare a wide variety of things. For example, Swift has a special type for storing dates called Date, and you can compare dates using the same operators: someDate < someOtherDate, for example.

We can even ask Swift to make our enums comparable, like this:

enum Sizes: Comparable {
    case small
    case medium
    case large

let first = Sizes.small
let second = Sizes.large
print(first < second)

That will print “true”, because small comes before large in the enum case list.

Hacking with Swift is sponsored by RevenueCat

SPONSORED Spend less time managing in-app purchase infrastructure so you can focus on building your app. RevenueCat gives everything you need to easily implement, manage, and analyze in-app purchases and subscriptions without managing servers or writing backend code.

Get Started

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

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: 5.0/5

Unknown user

You are not logged in

Log in or create account

Link copied to your pasteboard.