深入浅出Swift（2）—— 控制流

Swift除了具备C所有的控制流结构外，还具备了oc中没哟的 for...in...结构方便遍历数组，字典等。

【循环】

swift的循环提供了四种结构：

<1>for...in：常用来遍历数组，类似与c#中的forearch

var myArray = ["string1",123,456]
for i in myArray{
   println("item is \(i)")
}

var myArray = ["v1":"string1","v2":123,"v2":11.34]
for (name,value) in myArray{
    println("key name=\(name)   key value=\(value)")
}

<2>for...condition...increment：这个结构和oc的for一样。

for var i=0; i<10; i++{
   println("index is \(i)")
}

<3>while:和oc的while一样

while 1<2 {
  println("this is while loop")
}

<4>do...while:和oc的do...while一样

do{
  println("this is do while")
}while 1<2

【条件语句】

<1>if...else

if 1<2 {
  .......
}
else if 1<3{
  .......
}
else{
  .......
}

<2>switch

var num:Int

switch num {
   case 1:
   case 2:
       println("num is 2")
   case 3:
      println("num is 3")
   case 4,5,6:
      println("num is 4 or 5 or 6")
   default:
     println("num is not 1 or 2 or 3")
}