Swift: Convert enum value to String?

Not sure in which Swift version this feature was added, but right now (Swift 2.1) you only need this code:

enum Audience : String {
    case public
    case friends
    case private
}

let audience = Audience.public.rawValue // "public"

When strings are used for raw values, the implicit value for each case is the text of that case’s name.

[...]

enum CompassPoint : String {
    case north, south, east, west
}

In the example above, CompassPoint.south has an implicit raw value of "south", and so on.

You access the raw value of an enumeration case with its rawValue property:

let sunsetDirection = CompassPoint.west.rawValue
// sunsetDirection is "west"

Source.

The idiomatic interface for 'getting a String' is to use the CustomStringConvertible interface and access the description getter. Define your enum as:

enum Foo : CustomStringConvertible {
  case Bing
  case Bang
  case Boom
  
  var description : String { 
    switch self {
    // Use Internationalization, as appropriate.
    case .Bing: return "Bing"
    case .Bang: return "Bang"
    case .Boom: return "Boom"
    }
  }
}

In action:

 > let foo = Foo.Bing
foo: Foo = Bing
 > println ("String for 'foo' is \(foo)"
String for 'foo' is Bing

Updated: For Swift >= 2.0, replaced Printable with CustomStringConvertible

Note: Using CustomStringConvertible allows Foo to adopt a different raw type. For example enum Foo : Int, CustomStringConvertible { ... } is possible. This freedom can be useful.