Raw values can be strings,characters,or any of the integer or
floating-point number types

— Excerpt From: Apple Inc. “The Swift Programming Language.” iBooks. 07000,

所以你可以使用这样的代码：

enum StringEnum: String 
{
  case one = "one"
  case two = "two"
  case three = "three"
}

let anEnum = StringEnum(rawValue: "one")!

print("anEnum = \"\(anEnum.rawValue)\"")

注意：在每种情况后，您不需要写=“一”等。默认字符串值与案例名称相同，因此调用.rawValue只返回一个字符串

编辑

如果需要字符串值包含诸如作为大小写值的一部分无效的空格，则需要显式设置字符串。所以，

enum StringEnum: String 
{
  case one
  case two
  case three
}

let anEnum = StringEnum.one
print("anEnum = \"\(anEnum)\"")

给出

anEnum = “one”

但是如果你想要第一个显示“值一”，你将需要提供字符串值：

enum StringEnum: String 
{
  case one   = "value one"
  case two   = "value two"
  case three = "value three"
}