iOS Programming: The Big Nerd Ranch Guide, 7th Edition

Enumerations and the Switch Statement

An enumeration 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                              apple

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

let name: String
switch favoritePie {
case .apple:
    name = "Apple"                                           "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, whether explicitly or via a default case. Unlike in C, Swift switch cases do not fall through – only the code for the case that is matched is executed. (If ...