字符串

1.初始化

1.初始化

let str = "xx"   //不可变字符串

var mutableStr = "xx" //可变字符串

2.空值

var emptyStr = “”   //空串初始化

var anotherEmptyStr = String() //通过初始化函数初始化

3.空值判断

if str.isEmpty{

}

2.字符串修改与插入

var str = "xxx"

str += "aaa" //插入  

3.字符串长度

countElements函数

let unusalMenagerie = "a,b,c,d"

println("the count is \(countElements(unusalMenagerie))") 

4.字符串比较

let a = "xxxxxxxxxxxxx"

let b = "bbbbbbbbbbbb"

if(a == b){    //直接双等号即可判断

}