Swift学习1: String应用

Swift的变量/常量定义比C/C++/Delphi宽松得多,会随着初始化的值类型而定,当然可以用:type的方式指定数据类型,XCode非常智能,任何常量/变量未初始化,编译将不通过,将这 方面的失误堵截在运行前.

如:

var a:String;

NSLog("a:%@",a); //编译是不能通过的.

定义变量用var,定义常量用let,而delphi 则用var 和const,定义变量可以在变量后面加:type来指定变量数据类型,如 var num:Int32=1234,delphi也是这样的 ^_^

一般的string用法

下面是更详细的string用法(转载)

下面是转载,但swift3.0未须适用.

• 作者：Mandarava（鳗驼螺）

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=//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=//字符常量

3. 字符串的连接

   let str1=
   "mandarava."
   let str3=str1+str2 //=连接str1、str2
   //str3="hello,mandarava."
   //----------------------------------------
   let str4="(str1)(str2)" //str4="hello,0)">let strArray=["apple","orange",152)">"cherry"]
   let joinStr=",".join(strArray)
   //joinStr="apple,orange,cherry"

4. 字符串与字符的连接

   let char1:Character="o"
   "hell"
   let str2=str1+String(char1)
   //str2="hello"
   (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
   "(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
   str.characters{
    print(ch)
   }

7. 获取字符串中指定索引处的字符

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

8. 计算字符串长度length

   "@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,0)">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 range=str1.rangeOfString(str2)
    if range != nil{
     //包含
    }

11. 查找子串indexof

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

    str1=str1.uppercaseString
    //str1="HELLO,MANDARAVA."

14. 转换为小写字母lowercase

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

15. 截取字符串substring

    let str2=str1.substringFromIndex(advance(str1.startIndex,152)">6)) let str2=str1.substringFromIndex(str1.startIndex.advancedBy(//Swift 2.0
    //str2="mandarava."
    let str3=str1.substringToIndex(advance(str1.startIndex,152)">5)) let str3=str1.substringToIndex(str1.startIndex.advancedBy(let range=Range<String.Index>(start: advance(str1.startIndex,152)">6),end: advance(str1.endIndex,152)">-1)) String.Index>(start: str1.startIndex.advancedBy(end: str1.endIndex.advancedBy(let str4=str1.substringWithRange(range)
    //str4="mandarava"

16. 字符串修剪trim

    let str1=" mandarava.n "
    2=str1.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())
    3=str1.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet())
    //str3="mandarava.n"
    let charset=NSCharacterSet(charactersInString:" n")
    4=str1.stringByTrimmingCharactersInSet(charset)
    //str4="mandarava."

17. 字符串的分解子串split

    "boy,girl,man,woman"
    let str1Array=str1.componentsSeparatedByString()
    //str1Array=["boy",152)">" girl",152)">" man",152)">" woman"]
    var str2=
    )
    let str2Array=str2.componentsSeparatedByCharactersInSet(charset)
    //str2Array=["girl",152)">"man",152)">"10",152)">"20",152)">"30"]

18. 字符串替换replace

    var str1="My name is Mandarava."
    let subRange=Range(start: str1.startIndex,152)">end: advance(str1.startIndex,152)">2)) //Swift 1.2
    let subRange=Range(end: str1.startIndex.advancedBy(//Swift 2.0
    str1.replaceRange(subRange,152)">with: "Your")
    //str1="Your name is Mandarava."
    var str2=
    str2=str2.stringByReplacingOccurrencesOfString(withString: "鳗驼螺")
    //str2="hello,鳗驼螺."
    str2=str2.stringByReplacingOccurrencesOfString("鳗驼螺",152)">options: NSStringCompareOptions.CaseInsensitiveSearch,152)">range: nil)
    

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

    "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

（编辑：李大同）

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