Swift

1，if语句

if count >=3 {
    println("yes")
}else{
    println("no")
}

2，switch语句

（1）Swift中不需要在case块中显示地使用break跳出switch。如果想要实现C风格的落入特性，可以给需要的case分支插入fallthrough语句

var fruit = "apple"
switch fruit{
    case "apple":
        println("good")
        fallthrough
    case "banana","orange":
        println("great")
    default:
        println("bad")
}

（2）case分支还可以进行区间匹配

var age = 5
switch age {
    case 0...11:
        println("正太")
    case 12...30:
        println("少年")
    default:
        println("大叔")
}

（3）使用元组匹配（判断属于哪个象限）

let point = (2,2)
switch point {
    case (0,0):
        println("坐标在原点")
    case (_,0):
        println("坐标在x轴上")
    case (0,_):
        println("坐标在y轴上")
    case (-3...3, -3...3):
        println("坐标在长宽为6的正方形内")
    default:
        println("在什么地方")
}

（4）case中还可以使用where关键字来做额外的判断条件

var height = 1.72
switch height{
    case 1...3 where height == 1.72:
        println("case 1")
    case 1...3 where height == 2:
        println("case 2")
    default:
        println("default")
}

3，for循环语句

（1）for条件递增循环

for var i=1; i<100; i++ {
    println("(i)")
}

（2）for-in循环

for i in 1..<100{
    println("(i)")
}
 
//遍历数组元素
let numbers = [1,2,4,7]
for num in numbers{
    println("(num)")
}
 
//遍历字典
let nameOfAge = ["lily":18, "Candy":24]
for (aName, iAge) in nameOfAge{
    println("(aName) is (iAge)")
}
 
//遍历字符串的字符
for chare in "hangge" {
    println(chare)
}

4，while循环语句

while i<100 {
    i++
}
 
do{
    i++
}while i<100