Points:
- Basic format
- enum with type declaraion
- enum case with predefined value
- enum with function
- enum case with variable
Example 1: enum has type declaration and function
enum ImageEnum: String {
case img1 = "1"
case img2 = "2"
case img3 = "3"
func next() -> ImageEnum {
switch self {
case .img1: return .img2
case .img2: return .img3
case .img3: return .img1
}
}
}
print(ImageEnum.img1.next())
Example 2: the most basic format
enum MoveDirection {
case forward
case back
case left
case right
}
let a = MoveDirection.forward
print(a) // forward
print(type(of: a)) // MoveDirection
Example 3: basic format with type declaration, then you can access the rawValue attribute
enum MoveDirection: String {
case forward
case back
case left
case right
}
let a = MoveDirection.forward
print(a) // forward
print(type(of: a)) // MoveDirection
print(a.rawValue)
print(type(of: a.rawValue))
Example 4: with predefined value and you can also check the difference with a and a.rawValue.
enum MoveDirection : String {
case forward = "you moved forward"
case back = "you moved backwards"
case left = "you moved to the left"
case right = "you moved to the right"
}
let a = MoveDirection.forward
print(a) // forward
print(type(of: a)) // MoveDirection
print(a.rawValue)
print(type(of: a.rawValue))
Example 5: predefined value (implicit)
enum GolfScores : Int {
case HoleInOne = 1, Birdie, Boogie, Par4, Par5, Par6
func getScore() -> Int {
return self.rawValue
}
}
var shot = GolfScores.Birdie
print(shot) // this will print out 2
print(shot.getScore())
Example 6: enum case with variable and with an outside assistant function.
enum BankDeposit {
case inValue(Int, Int, Int) //hundreds,tens,ones
case inWords(String) //words
}
func makeDeposit(_ person:BankDeposit){
switch person{
case .inValue(let hundred, let tens, let ones):
print("deposited: \((hundred*100)+(tens*10)+(ones*1))")
case .inWords(let words):
print("deposited: \(words)")
}
}
var person1 = BankDeposit.inValue(1,2,5)
makeDeposit(person1) //prints deposited: 125
var person2 = BankDeposit.inWords("One Hundred Twenty Five")
makeDeposit(person2) //prints deposited: One Hundred Twenty Five
Example 7: enum case with variable without outside assistant function
enum BankDeposit {
case inValue(Int, Int, Int) //hundreds,tens,ones
case inWords(String) //words
}
var person1 = BankDeposit.inValue(1,2,5)
print(person1)
var person2 = BankDeposit.inWords("One Hundred Twenty Five")
print(person2)
Example 8: nested enum
enum PTEQuestionType {
enum PTEReadType: String {
case RA
func getFullName() -> String {
switch self {
case .RA:
return "Read aloud"
}
}
func getShortname() -> String {
return self.rawValue
}
}
}
let a = PTEQuestionType.PTEReadType.RA
print(a.getShortname())