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
}