一. 常用循环结构
循环: for, for_in, while, repeat_while
for循环
// 不需要添加括号
for var i = 0; i < 10; i++ {
> print(i)
>}```
>####forin循环
//1..<10: 表示开区间, 即1~9
for var number in 1..<10{
print(number)
}
//1...10: 表示闭区间, 即1~10
for var number in 1...10{
print(number)
}```
while循环
var j = 5
while j > 0{
j--
print(j)
}```
>####repeat_while(即: OC 中的do...while循环)
var i = 10
repeat {
print("repeat")
i--
}while i > 0```
循环遍历数组
var animal = ["a", "b", "c", "d", "e"]
for a in animal{
> print(a)
}```
>####循环遍历字典
animalDic = ["dog":"🐶", "cat":"🐱"]
//注意: 结果的参数类型
for (key, value) in animalDic{
print("key = (key), value = (value)")
}```
二. 常用的分支结构
- if , if ... else , switch...case
if, if ... else
>let flag:Bool = true
if flag == true{
> print("flage = \(flag)")
>}else{
> print("flage = ", false)
}```
>####2. switch ... case ( 默认自带 break)
//特点:
//1. switch中想要实现贯穿, 使用关键字fallthrough
let temp = 20
switch temp {
case 0 : print("为零")
fallthrough
case 1 : print("为1")
fallthrough
default : print("你猜")
}
//2. case 后面可以是条件范围
switch temp {
case var a where temp >= 0 && temp < 10 :
a = 20
print("a = (a)")
default : print("你猜")
}
//3. case后面可以是添加范围
switch temp {
case 0...10 :
print("0~9")
case 10...20:
print("10~20")
default : print("你猜")
}
//4. switch ... case 可以匹配一个元组
let point = (10, 10)
switch point {
case (10, 0):
print("case1")
case (0, 10):
print("case2")
case (10, 10):
print("case3")
default:
print("other")
}```
