NEW! Master Swift design patterns with my latest book! >>

< Previous: Enum associated values   Next: Complex types: Summary >

Enum raw values

Sometimes you need to be able to assign values to enums so they have meaning. This lets you create them dynamically, and also use them in different ways.

For example, you might create a Planet enum that stores integer values for each of its cases:

enum Planet: Int {
    case mercury
    case venus
    case earth
    case mars
}

Swift will automatically assign each of those a number starting from 0, and you can use that number to create an instance of the appropriate enum case. For example, earth will be given the number 2, so you can write this:

let earth = Planet(rawValue: 2)

If you want, you can assign one or more cases a specific value, and Swift will generate the rest. It’s not very natural for us to think of Earth as the second planet, so you could write this:

enum Planet: Int {
    case mercury = 1
    case venus
    case earth
    case mars
}

Now Swift will assign 1 to mercury and count upwards from there, meaning that earth is now the third planet.

Become a Swift expert

I wrote a book called Pro Swift that's dedicated to helping you master the Swift language, and it includes seven hours of video demonstrating each technique!

< Previous: Enum associated values   Next: Complex types: Summary >
MASTER SWIFT NOW
Buy Practical iOS 12 Buy Pro Swift Buy Swift Design Patterns Buy Practical iOS 11 Buy Swift Coding Challenges Buy Server-Side Swift (Vapor Edition) Buy Server-Side Swift (Kitura Edition) Buy Hacking with macOS Buy Advanced iOS Volume One Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with Swift Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let me know!

Average rating: 3.5/5

Click here to visit the Hacking with Swift store >>