如何为数组进行切换？

Question

这是我的代码:

var animalArray = ["cow","pig"]

switch animalArray {
case ["cow","pig"],["pig","cow"]:
    println("You Win!")
default:
    println("Keep Trying")

我得到错误:"类型'数组'不符合协议'IntervalType'"的行"case ["cow","pig"],["pig","cow"]:".我究竟做错了什么？

Answer 1

该switch声明需要一个Int. 想一想：

var animalDict: [String: Int] = ["cow": 0,"pig": 1]
var animalSelection: Int = animalDict["cow"]!

switch animalSelection {
case 0:
    println("The Cow Wins!")
case 1:
    println("The Pig Wins!")
default:
    println("Keep Trying")
}

//prints "The Cow Wins!"

编辑1：

感谢大家的评论。我认为这是更健壮的代码：

var animalDict: [String: Int] = ["cow": 0,"pig": 1]
var animalSelection: Int? = animalDict["horse"]

if animalSelection as Int? != nil {
   switch animalSelection! {
   case 0:
       println("The Cow Wins!")
   case 1:
       println("The Pig Wins!")
   default:
       println("Keep Trying")
   }
} else {
    println("Keep Trying")
}

//prints "Keep Trying"

The Cow Wins如果我说：它仍然会打印：

var animalSelection:Int? = animalDict["cow"]

编辑2：

根据@AirSpeedVelocity的评论，我测试了以下代码。比我自己的代码优雅得多：

var animalDict: [String: Int] = ["cow": 0,"pig": 1]
var animalSelection = animalDict["horse"]

switch animalSelection {
case .Some(0):
    println("The Cow Wins!")
case .Some(1):
    println("The Pig Wins!")
case .None:
    println("Not a valid Selection")
default:
    println("Keep Trying")
}