swift枚举

以下是指南针四个方向的一个例子: 

enum CompassPoint {

case North
case South
case East

case West

} 

 

多个成员值可以出现在同一行上,用逗号隔开:

enum Planet {
case Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

} 

匹配枚举值和 语句 你可以使用 语句匹配单个枚举值:

Compass

directionToHead

directionToHead = .South switch directionToHead { case .North:

print("Lots of planets have a north") case .South: 

print("Watch out for penguins") case .East:

print("Where the sun rises") case .West:

print("Where the skies are blue") }

// 输出 "Watch out for penguins” 

当不需要匹配每个枚举成员的时候,你可以提供一个默认

let somePlanet = Planet.Earth switch somePlanet {
case .Earth:

print("Mostly harmless") default:

print("Not a safe place for humans") }

// 输出 "Mostly harmless”