一·控制流
1.for-in
遍历数组
let names = ["swift","Object-C","golang"]
for name in names {
print("Hello (name)")
}
遍历字典
let citys = ["Guangzhou":1,"ShenZhen":2]
for a , b in citys{
print("city: (a) city:(b)")
}
遍历一段区域
for index in 1...5{}
次幂运算例子
let base = 3
let power = 10
var answer = 1
for _ in 1...power{
answer *= base
}
while循环
while (1){
//无限循环
}
repeat {
//循环前先执行一次代码
}while (condition)
神似do-while
if判断
if (条件){}
Switch 判断
switch ()
case:
case:
default:
guard提前退出
guard bool else{ print() }
不同于if语句，guard永远有一个else语句，如果条件不为真那么执行else
