swift:continue,break,fall through,return 简单说明

swift 有4个 控制转移句： continue , break, fall through, return。

1. continue:结束本次循环，执行下个循环，不跳出循环。

let puzzleInput = "hello world“

var puzzleOutput = ""

for character in puzzleInput {

switch character {

case "a", "e", "i", "u", " " :

continue

default:

puzzleOutput += character

}

}

打印结果： hllwrld

2. break:立即结束整个流程控制语句执行。

let numberSymbol: Character = "三"

var possibleIntegerValue: Int?

switch numberSymbol {

case "1","١", "一","๑":

possibleIntegerValue = 1

case "2","٢", "二","๒":

        possibleIntegerValue = 2
    case"3","٣","三","๓":

        possibleIntegerValue =3

    case"4","٤","四","๔":
        possibleIntegerValue = 4
    default:

   break

}

iflet integerValue = possibleIntegerValue {

            println("The integer value of \(numberSymbol) is\(integerValue).")
    }else {
            println("An integer value could not be found for \(numberSymbol)")

}

}

3.Fallthrough:在switch中，在不判断下个case的条件下，执行下个case里的语句

let integerToDescribe =5

       var description = "The number \(integerToDescribe) is"

        switch integerToDescribe {
        case2,3,5,7,11,13,17,19:
            description += " a prime number, and also"
            fallthrough
        default:
            description += " an integer"

        }

       println(description)

打印结果：The number 5 is a prime number, and also an integer

4.return: 是方法的返回。