Swift 枚举

• 简单的枚举

enum CompassPoint {
    case north
    case south
    case east
    case west
}
var directionToHead = CompassPoint.north
directionToHead = .east

enum Planet {
    case mercury,venus,earth,mars
}

• 遵循CaseIterable 协议可以获得枚举元素

enum Beverage:CaseIterable {
    case coffee,tea,juice
}
Beverage.allCases.count
for item in Beverage.allCases {
    print(item)
}
/*
 coffee
 tea
 juice
 */

enum CompassPoint:String {
    case north
    case south
    case east
    case west
}
CompassPoint.west.rawValue // "west"

enum Planet:Int {
    case mercury = 1,venus,earth,mars
}
Planet.earth.rawValue // 3