Programming in Swift: Functions & Types

Jan 4 2022 Swift 5.5, iOS 15, Xcode 13

Part 3: Enumerations

21. Enumerations

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Previous episode: 20. Introduction Next episode: 22. Challenge: Enumerations

Update Notes: This course was originally recorded in 2019. It has been reviewed and all content and materials updated as of October 2021.

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So, when I say “a specific set of related, discrete values.” What do I mean? Some commons examples are cardinal directions, colors, or card suits. State machines, like a traffic light, are also a great use case.

enum Month {
  
}
case january
case february
case january, february, march, april, may, june, july, august, september, october, november, december
let month = Month.october
let month: Month = Month.october
let month: Month = .october
enum Month😺: Int🛑 {
case january😺 = 1🛑,
func monthsUntilJingleBells(from month: Month) -> Int 
}
  Month.december.rawValue - month.rawValue
}
monthsUntilJingleBells(from: .november)
let rawMonth = Month(rawValue: 3)

String Raw Values

Let’s set up one more Enumeration! This one will be for seasons

enum Season
enum Season: String {

}
enum Season: String {
  case winter
  case spring
  case summer 
  case autumn
}
enum Season: String {
  😺/// ☃️
  case winter
  
  😺/// 🌸
  case spring
  
  😺/// 😎
  case summer
  
  😺/// 🍂
  case autumn
}
Season.
Season.winter
Season.winter😺.rawValue

CaseIterable

Sometimes you might want to do something like figure out how many cases an enumeration has, or iterate through those cases and do something with each of them. You can absolutely do that, you just need to make your enumeration conform to the CaseIterable protocol.

enum Season: String😺, CaseIterable🛑 {
Season.allCases
Season.allCases😺.filter {
  $0.rawValue.first == "s"
}🛑