Swift-3-字符串和字符

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

import UIKit

var someString = "some string literal value"
someString += "another"

// 初始化空字符串 2种方式，得出的结果一致
var emptyString = ""
var anotherEmptyString = String()

if emptyString.isEmpty {
    println("emptyString is empty")
}

// 可变字符串
var varibleString = "hosrse"
varibleString += "and carriage"

let constantString = "hignlander"
//constantString += "anything" // 字符串常量不能修改，出错

// swift中字符串是值类型 value type

// 连接字符串
var string1 = "hello"
var string2 = " there"
var welcome = string1 + string2

// 向字符串后添加字符
let exclamationMark : Character = "!"
welcome.append(exclamationMark)

// 字符串插值 ()
let multiplier = 3
let message = "(multiplier) times 2.5 is (Double(multiplier) * 2.5)"