Swift-5-流程控制

// Playground - noun: a place where people can play



import UIKit



// For-In 循环

// 1 遍历数字区间

for index in 1...5 {

    println("\(index) times 5 is \(index)")

}



// 2 遍历数组

let names = ["Anna", "Alex", "Brain", "Jack"]

for name in names {

    println("hello, \(name)")

}



// 3 遍历字典

let numberOfLegs = ["spider" : 8, "ant" : 6, "cat" : 4]

for (name, legCount) in numberOfLegs {

    println("\(name) has \(legCount) legs")

}



// 4 遍历字符

for character in "hello" {

    println(character)

}



// For 循环

for var index = 0; index < 3; index++ {

    println("index is \(index)")

}



// While do-while

var i = 0

do {

    i++

} while (i < 3)



while (i < 5) {

    i++

}



// 条件语句 Conditional Statements

var temperatureInFahrenheit = 30

if temperatureInFahrenheit <= 32 {

    println("It's very cold")

}



switch temperatureInFahrenheit {

    case 1...20:

        println("1...20")

    case 23, 30:

        println("come here")

        fallthrough // 默认不会进入下一个判断，加上这个关键字可以让匹配直接进入下一个

    default:

        println("default")

        break // 跳出switch

}



var somePoint = (1, 1)

switch somePoint {

    case let (x, y) where x == y:

        println("equal")

    default:

        break

}