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(guò)判斷單一的條件開(kāi)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(lèi)似于if語(yǔ)句，基于布爾值表達(dá)式來(lái)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 !"