Enum associated values

As well as storing a simple value, enums can also store associated values attached to each case. This lets you attach additional information to your enums so they can represent more nuanced data.

For example, we might define an enum that stores various kinds of activities:

enum Activity {
    case bored
    case running
    case talking
    case singing
}

That lets us say that someone is talking, but we don’t know what they are talking about, or we can know that someone is running, but we don’t know where they are running to.

Enum associated values let us add those additional details:

enum Activity {
    case bored
    case running(destination: String)
    case talking(topic: String)
    case singing(volume: Int)
}

Now we can be more precise – we can say that someone is talking about football:

let talking = Activity.talking(topic: "football")

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