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。

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

字符的定义

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

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"

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"

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=?"

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)
}

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"

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

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

是否包含子串contains

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

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

首字母大写capitalized

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

转换为大写字母uppercase

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

转换为小写字母lowercase

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

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"

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."

字符串的分解子串split @H_282_403@"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"]

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)

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

Swift学习1: String应用

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