Swift字符串常用操作总结

版本2：增加了Swift 2.0的语法，与Swift 1.2的语法相比，主要是：advance方法变成了advancedBy方法（但不是简单替换）；没有了count方法，count(str)需要变成str.characters.count等。

1. 字符串的定义

   var str1="hello, mandarava." //字符串变量
   let str2="hello, mandarava." //字符串常量
   let str3="" //空字符串
   let str4=String() //空字符串

2. 字符的定义

   var char1:Character="m" //字符变量
   let char2:Character="m" //字符常量

3. 字符串的连接

   let str1="hello, "
   let str2="mandarava."
   let str3=str1+str2 //=连接str1、str2
   //str3="hello, mandarava."
   //----------------------------------------
   let str4="(str1)(str2)" //=连接str1、str2
   //str4="hello, mandarava."
   //----------------------------------------
   let strArray=["apple", "orange", "cherry"]
   let joinStr=",".join(strArray)
   //joinStr="apple,orange,cherry"

4. 字符串与字符的连接

   let char1:Character="o"
   var str1="hell"
   let str2=str1+String(char1)
   //str2="hello"
   //----------------------------------------
   let str3="(str1)(char1)"
   //str3="hello"
   //----------------------------------------
   str1.append(char1)
   //str1="hello"

5. 字符串与其它类型值的连接

   let xx=10
   let yy=10.8
   let str1="(xx)+(yy)=?"
   //str1="10+10.8=?"
   //----------------------------------------
   let str2=String(format: "%i+%.1f=?", xx, yy)
   //str2="10+10.8=?"

6. 字符串枚举字符

   //Swift 1.2
   let str="mandarava"
   for ch in str{
    println(ch)
   }
   //-----------------------
   //Swift 2.0
   let str="mandarava"
   for ch in str.characters{
    print(ch)
   }

7. 获取字符串中指定索引处的字符

   let str="Mandarava"
   let chr=str[advance(str.startIndex,2)] //Swift 1.2 //chr:Character="n"
   let chr=str[str.startIndex.advancedBy(2)] //Swift 2.0 //chr:Character="n"

8. 计算字符串长度length

   let str="@鳗驼螺"
   let len1=count(str) //swift 1.2 //=4 
   let len2=str.characters.count //swift 2.0 //=4 
   let blen=str.lengthOfBytesUsingEncoding(NSUTF8StringEncoding) //=10

9. 字符串比较

   let str1="hello,"
   let str2="mandarava."
   let str3="hello,mandarava."
   let comp1 = str1==str2 //false
   let comp2 = str1+str2 == str3 //true
   let comp3 = str1 < str2 //true
   let comp4 = str1 != str2 //true

10. 是否包含子串contains

    let str1="hello,mandarava."
    let str2="mandarava"
    let range=str1.rangeOfString(str2)
    if range != nil{
     //包含
    }

11. 查找子串indexof

    var str="hi,Mandarava."
    let range=str.rangeOfString("Mandarava", options: NSStringCompareOptions.allZeros) //Swift 1.2
    let range=str.rangeOfString("Mandarava", options: NSStringCompareOptions()) //Swift 2.0
    let startIndex=range?.startIndex //=3

12. 首字母大写capitalized

    var str1="mandarava is a flower."
    str1.capitalizedString
    //str1="Mandarava Is A Flower.

13. 转换为大写字母uppercase

    var str1="hello, mandarava."
    str1=str1.uppercaseString
    //str1="HELLO, MANDARAVA."

14. 转换为小写字母lowercase

    var str1="HELLO, MANDARAVA."
    str1=str1.lowercaseString
    //str1="hello, mandarava."

15. 截取字符串substring

    let str1="hello,mandarava."
    let str2=str1.substringFromIndex(advance(str1.startIndex, 6)) //Swift 1.2
    let str2=str1.substringFromIndex(str1.startIndex.advancedBy(6)) //Swift 2.0
    //str2="mandarava."
    //----------------------------------------
    let str3=str1.substringToIndex(advance(str1.startIndex, 5)) //Swift 1.2
    let str3=str1.substringToIndex(str1.startIndex.advancedBy(5)) //Swift 2.0
    //str3="hello"
    //----------------------------------------
    let range=Range<String.Index>(start: advance(str1.startIndex, 6), end: advance(str1.endIndex, -1)) //Swift 1.2
    let range=Range<String.Index>(start: str1.startIndex.advancedBy(6), end: str1.endIndex.advancedBy(-1)) //Swift 2.0
    let str4=str1.substringWithRange(range)
    //str4="mandarava"

16. 字符串修剪trim

    let str1=" mandarava.
     "
    let str2=str1.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())
    //str2="mandarava."
    //----------------------------------------
    let str3=str1.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet())
    //str3="mandarava.
    "
    //----------------------------------------
    let charset=NSCharacterSet(charactersInString:" 
    ")
    let str4=str1.stringByTrimmingCharactersInSet(charset)
    //str4="mandarava."

17. 字符串的分解子串split

    var str1="boy, girl, man, woman"
    let str1Array=str1.componentsSeparatedByString(",")
    //str1Array=["boy", " girl", " man", " woman"]
    var str2="boy,girl,man 10 20 30"
    let charset=NSCharacterSet(charactersInString:", ")
    let str2Array=str2.componentsSeparatedByCharactersInSet(charset)
    //str2Array=["boy", "girl", "man", "10", "20", "30"]

18. 字符串替换replace

    var str1="My name is Mandarava."
    let subRange=Range(start: str1.startIndex, end: advance(str1.startIndex, 2)) //Swift 1.2
    let subRange=Range(start: str1.startIndex, end: str1.startIndex.advancedBy(2)) //Swift 2.0
    str1.replaceRange(subRange, with: "Your")
    //str1="Your name is Mandarava."
    var str2="hello, Mandarava."
    str2=str2.stringByReplacingOccurrencesOfString("Mandarava", withString: "鳗驼螺")
    //str2="hello, 鳗驼螺."
    str2=str2.stringByReplacingOccurrencesOfString("鳗驼螺", withString: "Mandarava", options: NSStringCompareOptions.CaseInsensitiveSearch, range: nil)
    //str2="hello, Mandarava."

19. string转换为Int/Long/Float/Double/Bool等

    var str1="100"
    var i=str1.toInt()! //Swift 1.2 //=100 
    var i=(str1 as NSString).integerValue //Swift 2.0 //=100
    var i=(str1 as NSString).intValue //=100
    var l=(str1 as NSString).longLongValue //=100
    var str2="10.8"
    var f=(str2 as NSString).floatValue //=10.8
    var d=(str2 as NSString).doubleValue //=10.8
    var str3="true"
    var b=(str3 as NSString).boolValue //=true

文／鳗驼螺（简书作者）
原文链接：http://www.jianshu.com/p/52e7580166ff
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