Iterate the values of Enum type with Swift1.2

extensions.swift

enum SoundEffectType:Int {
    case Whitsle = 0,
         Finish,
         CDThree,
         CDTwo,
         CDOne,
         CDGo,
         Good,
         Great,
         Excellent,
         Fantastic,
         Marvelous,
         Poor,
         OK,
         HighScore,
         LevelUp
    
    class EnumGenerator:GeneratorType {
        var i = 0
        typealias Element = SoundEffectType
        func next() -> Element? {
            let r = SoundEffectType(rawValue: i)
            i += 1
            return r
        }
    }
    
    static func enumerate() -> SequenceOf<SoundEffectType> {
        return SequenceOf<SoundEffectType>({ EnumGenerator() })
    }

}