Hands-On Design Patterns with Swift

Raw type enums

A raw type is a base type for all enumeration members; in our example, we can hardcode presets for our dimming, as follows:

enum LightLevel: String {    case quarter    case half    case threequarters}let state: State<LightLevel> = .dimmed(.half)

Thanks to the generic implementation and the fact that String is equatable, we can use this raw value in our dimmed state.

With the LightLevel enum, which has a raw type of String, the compiler will use the member name as the underlying raw value:

LightLevel.half.rawValue == “half” // == true

You can override these by specifying them, as follows:

enum LightLevel: String {    case quarter = “1/4”    case half = “1/2”    case threequarters = “3/4”}

When using Int as a raw type, the underlying raw values ...