Swift字符串类型

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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、空值推断

 

if emptyString.isEmpty{
 
println("Nothing to see here")
 
}

 

 

 

 

字符串改动

 

var 声明的能够改动，let 不能改动。

 

 

 

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")

比較字符串相等

 

 

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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