Swift字符串类型

字符串初始化

 1、初始化

let  someString        =   "Some      string    literalvalue"



let wiseWords = ""Imagination is moreimportant than knowledge" -Einstein" let  dollarSign      =   "x24"                  //  $,
Unicodescalar U+0024

let  blackHeart       =   "u2665"               //  ♥,
Unicodescalar U+2665

let  sparklingHeart        =  "U0001F496"           //

, Unicode scalarU+1F496

2、空值

var emptyString = ""                                //
空串初始化
var anotherEmptyString = String()              //  通 过初始化函数初始化

3、空值判断

if emptyString.isEmpty{

println("Nothing to see here")

}

字符串修改

var 声明的可以修改，let 不能修改。

var variableString = "Horse" variableString+= " and carriage"




let constantString = "Highlander" constantString  += "  and   another

Highlander" //错误

字符串插入

let multiplier = 3

let message = "(multiplier) times 2.5 is
(Double(multiplier) * 2.5)"

字符串长度

使用 countElements函数。

let  unusualMenagerie            =  "Koala     , Snail, Penguin,Dromedary" println("unusualMenagerie                     has
(countElements(unusualMenagerie))
characters")

比较字符串相等

let quotation = "We're a lot alike, you and I."let sameQuotation = "We're a lot alike, youand I."


if quotation == sameQuotation {

println("These         two       strings      areconsidered equal")

}

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