Swift 4 学习

更新时间：2017-8-16

一、基础知识笔记

/**
 * Swift 4.0 学习
 */

import UIKit

var a = ""

var b = " "

a.isEmpty
b.isEmpty

b.count

var ruo: Character = "其"
let words = "中国人有人人械"
for heword in words {
    print("字: ",heword)
}

let a = "便是"
let b = "人间"
let c = "好时节"

var d = a + b + c

let smil = "小明"
d.append(smil)

print("\" \\ \n a \'")

多行字符串
let code = """

js test


这是一个swift多行字符串

点击按钮更新文字



"""

let name = "李白"
let type = "G"
let num = 168
let desc = "长安"
let deTi = "洛阳"
let price = 380

let msg = """
尊敬\(name)的乘客，您已订购\(type)\(num)\(desc)到\(deTi)的往返票，需要支付\(380 * 2)元。
"""
let a = """
海客谈瀛洲
烟涛微茫信难求
越人语天姥
云霞论坛系统好
世博五月延迟成
天台一万八千张
对此欲倒东南倾
"""

索引
a.startIndex
a.endIndex
a.count

a[a.startIndex]

a[a.index(after: a.startIndex)]

a[a.index(before: a.endIndex)]

a[a.index(a.startIndex, offsetBy: 3)]
a[a.index(a.endIndex, offsetBy: -3)]

for index in a.indices {
    print(a[index])
}

for b in a {
    print(b)
}

插入和删除
var a = "世界尽快头"

a.insert(",", at: a.endIndex)

let b = "难分离李克勤春哥?"

a.insert(contentsOf: b, at: a.endIndex)

//删除 remove
//a.remove(at: a.index(before: a.endIndex))

//删除一个范围
let str = a.index(a.endIndex, offsetBy: -(b.count))

let bRange = str..