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")

}