列挙enumの中身を表示する。rawValueではその意味が判らんので！ただし、このソースの意味がよく判らん。要解読。

displayEnum.swift

import Foundation

func iterateEnum<T: Hashable>(_: T.Type) -> AnyGenerator<T> {
    var cast: (Int -> T)! // reference to clousure
//print(($0).dynamicType)
// what is $0 ?, Int, 0, 1, 2, 3, 4 for nil
    switch sizeof(T) {
    case 0: return anyGenerator(GeneratorOfOne(unsafeBitCast((), T.self)))
    case 1: cast = { unsafeBitCast(UInt8(truncatingBitPattern: $0), T.self) }
// print($0.dynamicType);print($0)
    case 2: cast = { unsafeBitCast(UInt16(truncatingBitPattern: $0), T.self) }
    case 4: cast = { unsafeBitCast(UInt32(truncatingBitPattern: $0), T.self) }
    case 8: cast = { unsafeBitCast(UInt64($0), T.self) }
    default: fatalError("cannot be here")
    }
print(UInt8(truncatingBitPattern: 1023)) // 255
print(UInt16(truncatingBitPattern: 1023))// 1023
//print(sizeof(T))

    var i = 0
    return anyGenerator {
        let next = cast(i)
        return next.hashValue == i++ ? next : nil
    }
}

enum Suit:String {
    case Spades = "♠♠"
    case Hearts = "♥"
    case Diamonds = "♦"
    case Clubs = "♣"
}
//print(iterateEnum(Suit))
for f in iterateEnum(Suit) {
  print(f.rawValue)
}


func iterateEnum2<T: Hashable>(_: T.Type) -> AnyGenerator<T> {
    var i = 0
    return anyGenerator {
        let next = withUnsafePointer(&i) { UnsafePointer<T>($0).memory }
//        print(i)
//        print(next.dynamicType)
        return next.hashValue == i++ ? next : nil
    }
}

var i = 0

//var voidPtr: UnsafePointer<Suit> = unsafeBitCast(0, UnsafePointer<Suit>.self)
//print(voidPtr.memory)


print(withUnsafePointer(&i){(p: UnsafePointer<Int>) -> Suit in
  var voidPtr: UnsafePointer<Suit> = unsafeBitCast(p, UnsafePointer<Suit>.self)
  print(i)
  print(p.memory)
  print(voidPtr[0], voidPtr[5])
  return voidPtr.memory})
i++
print(withUnsafePointer(&i){(p: UnsafePointer<Int>) -> Suit in
  var voidPtr: UnsafePointer<Suit> = unsafeBitCast(p, UnsafePointer<Suit>.self)
  print(i)
  print(p.memory)
  return voidPtr.memory})
print(withUnsafePointer(&i){UnsafePointer<Suit>($0).memory})
//print(UnsafePointer<Suit>(&i).memory)
print("--------------")

for f in iterateEnum2(Suit) {
  print(f.rawValue)
//  print(f.dynamicType)
}
// AnyGenerator<T>のインスタンスにはanyGeneratorに与えたclousureが含まれる
// for..in loopはAnyGeneratorのインスタンスのnext()インスタンスメソッド
// を呼び出す。
// iterateEnumはgenerate()->AnyGenerator<T>と同じジェネレータである。