Cocoa Programming for OS X: The Big Nerd Ranch Guide

Enumerations and the Switch Statement

An enumeration (“enum” for short) is a type with a discrete set of values. Define an enum describing pies:

enum PieType {
    case Apple
    case Cherry
    case Pecan
}

let favoritePie = PieType.Apple

When the compiler expects the enum type, you can skip the full type name. For example:

var piesToBake: [PieType] = []
piesToBake.append(.Apple)

Swift has a powerful switch statement which, among other things, is great for matching on enum values:

let name: String
switch favoritePie {
case .Apple:
    name = "Apple"
case .Cherry:
    name = "Cherry"
case .Pecan:
    name = "Pecan"
}

The cases for a switch statement must be exhaustive: each possible value of the switch expression must be accounted for, ...