How to make an enum conform to a protocol in Swift?

Question

Swift documentation says that classes, structs, and enums can all conform to protocols, and I can get to a point where they all conform. But I can't get the enum to behave quite like the class and struct examples:

protocol ExampleProtocol {     var simpleDescription: String { get set }     mutating func adjust() }  class SimpleClass: ExampleProtocol {     var simpleDescription: String = "A very simple class."     var anotherProperty: Int = 69105      func adjust() {         simpleDescription += " Now 100% adjusted."     } }  var a = SimpleClass() a.adjust() let aDescription = a.simpleDescription  struct SimpleStructure: ExampleProtocol {     var simpleDescription: String = "A simple structure"      mutating func adjust() {         simpleDescription += " (adjusted)"     } }  var b = SimpleStructure() b.adjust() let bDescription = b.simpleDescription  enum SimpleEnum: ExampleProtocol {     case Base      var simpleDescription: String {         get {             return "A Simple Enum"         }         set {             newValue         }     }      mutating func adjust() {         self.simpleDescription += ", adjusted"     } }  var c = SimpleEnum.Base c.adjust() let cDescription = c.simpleDescription 

I haven't figured out how to get the simpleDescription to change as a result of calling adjust(). My example obviously won't do that because the getter has a value hard-coded, but how can I set a value for the simpleDescription while still conforming to the ExampleProtocol?

Answer 1

This is my attempt:

protocol ExampleProtocol {     var simpleDescription: String { get }     mutating func adjust() }  enum ExampleEnum : ExampleProtocol {     case Base, Adjusted      var simpleDescription: String {         return self.getDescription()     }      func getDescription() -> String {         switch self {         case .Base:             return "A simple description of enum"         case .Adjusted:             return "Adjusted description of enum"         }     }      mutating func adjust() {         self = ExampleEnum.Adjusted     } }  var c = ExampleEnum.Base c.adjust() let cDescription = c.simpleDescription 

Answer 2

Here is my take at it.

As this is an enum and not a class, you have to think different(TM): it is your description that has to change when the "state" of your enum changes (as pointed out by @hu-qiang).

enum SimpleEnumeration: ExampleProtocol {   case Basic, Adjusted    var description: String {     switch self {     case .Basic:       return "A simple Enumeration"     case .Adjusted:       return "A simple Enumeration [adjusted]"     }   }    mutating func adjust()  {     self = .Adjusted   } }  var c = SimpleEnumeration.Basic c.description c.adjust() c.description 

Hope that helps.