Enumerate

Define the enumeration

enum Day {
  case monday
  case tuesday
  case wednesday
  case thursday
  case friday
  case saturday
  case sunday
}

let casualWorkday: Day = .friday

Switch statement

enum Dessert {
  case cake(flavor: String)
  case vanillaIceCream(scoops: Int)
  case brownie
}

let customerOrder: Dessert = .cake(flavor: "Red Velvet")
switch customerOrder {
  case let .cake(flavor):
    print("You ordered a \(flavor) cake")
  case .brownie:
    print("You ordered a chocolate cake")
}
// prints: "You ordered a red velvet cake"

CaseIterable

enum Season: CaseIterable {
  case winter
  case spring
  case summer
  case falls
}

for season in Season.allCases {
  print(season)
}

Add conformance to the CaseIterable protocol to access the allCases property, which returns an array of all cases of the enumeration

Original value

enum Beatle: String {
  case john paul george ringo
}

print("The Beatles are \(Beatle.john.rawValue).")
// print: The Beatles are john.

Related values

enum Dessert {
  case cake(flavor: String)
  case vanillaIceCream(scoops: Int)
  case brownie
}

let order: Dessert = .cake(flavor: "Red Velvet")

instance method

enum Traffic {
  case light
  case heavy

  mutating func reportAccident() {
    self = .heavy
  }
}

var currentTraffic: Traffic = .light

currentTraffic.reportAccident()
// currentTraffic is now .heavy

Just like classes and structs, enumerations can have instance methods. If an instance method mutates the value of the enum, it needs to be marked mutating

Initialize from primitive value

enum Hello: String {
  case english = "Hello"
  case japanese = "Hello!"
  case emoji = "👋"
}
let hello1 = Hello(rawValue: "Hello!")
let hello2 = Hello(rawValue: "Привет")
print(hello1) // Optional(Hello.japanese)
print(hello2) // nil

Computed properties

enum ShirtSize: String {
  case small = "S"
  case medium = "M"
  case large = "L"
  case extraLarge = "XL"
  var description: String {
    return "The size of this shirt is \(self.rawValue)"
  }
}

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