How to add associated values to enums
Swift version: 5.1
Enums with associated values let you associate extra data with an enum case. This helps make them significantly more useful, because we can create gradations of cases rather than have them be absolute.
For example, we could create a Weather enum that can store various weather types: sunny, cloudy, windy, and rainy. However, that doesn’t really describe those conditions very well – how cloudy is it? Is it gale force winds or just a breeze? Is the rain definitely going to happen, or is it a fairly remote chance?
With enum associated values we can describe these situations more accurately. For example:
enum Weather {
case sunny
case cloudy(coverage: Int)
case windy(speed: Int)
case rainy(chance: Int)
}That leaves “sunny” as a simple value, but the other three all have associated values – how cloudy it is, what the speed of the wind is, and how likely the rain is.
Using those values we can now create instances of those enums:
let london = Weather.cloudy(coverage: 90)
let gusty = Weather.windy(speed: 10)
let guaranteedRain = Weather.rainy(chance: 100)SAVE 20% ON iOS CONF SG The largest iOS conference in Southeast Asia is back in Singapore for the 5th time in January 2020, now with two days of workshops plus two days of talks on SwiftUI, Combine, GraphQL, and more! Save a massive 20% on your tickets by clicking on this link.
Available from iOS 8.0 – learn more in my book Pro Swift
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