1： For-in 循環(huán)
let arr = ["張三","李四","王二"]
fornameinarr {
print(name)
}
//張三
//李四
//王二
2: While 循環(huán)
while循環(huán)通過判斷單一的條件開始。如果條件為true，語(yǔ)句的合集就會(huì)重復(fù)執(zhí)行直到條件變?yōu)閒alse。(條件符合接著遍歷， 條件不符跳出循環(huán))
var num:Int=5
while num > 0 {
num ?-= 1
}
print(num) ? ? ?// 0
3：If 語(yǔ)句
let name = "haha"
if ?name == "haha" {
print("true")
} else {
print("false")
}
// true
4: Switch 語(yǔ)句
let num = 5
var str:String
switch num {
case -1...0:
str ="bad1"
case1...4:
str ="bad2"
case5..<10:
str ="good"
default:
str ="bad3"
}
print(str) ? ? ? ? ?// "good"
5: guard -- else 語(yǔ)句
guard語(yǔ)句，類似于if語(yǔ)句，基于布爾值表達(dá)式來執(zhí)行語(yǔ)句. guard語(yǔ)句總是有一個(gè)else分句——else分句里的代碼會(huì)在條件不為真的時(shí)候執(zhí)行。
let person = ["name":"gouzi"]
guard let name = person["name"] else {
return
}
print("Hello\(name) !")? ? ? // "Hello gouzi !"
