Swift：将枚举值转换为String？

给出以下枚举：

enum Audience {
    case Public
    case Friends
    case Private
}

如何从观众常数下面得到字符串“公共”？

let audience = Audience.Public

不知道在哪个Swift版本中添加了这个功能，但现在(Swift 2.1)，你只需要这个代码：

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.

[…]

06001

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:

06002

07000