Swift - 字符串(String)用法详解

下面对String常用的属性和方法做个总结

1,判断是否为空:isEmpty
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var str:String
if str.isEmpty{
}

2,获取字符数量:countElements

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let str = "hangge.com"
println("\(countElements(str))个字符")

3,检查字符串是否有特定前缀/后缀:hasPrefix/hasSuffix

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var str = "hangge.com"
if str.hasSuffix(".com"){
}

4,还可以用“\()”在字符串里包裹变量,常量

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let name = "hangge.com"
let msg = "欢迎来到 \(name)"

5,大小写转换:

通过字符串的uppercaseString、lowercaseString、capitalizedString属性来访问一个字符串的大写/小写/首字母大写
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let str = "Welecome to hangge.com"
         
var uppercase = str.uppercaseString  //WELECOME TO HANGGE.COM
var lowercase = str.lowercaseString  //welecome to hangge.com
var capitalized = str.capitalizedString  //Welecome To Hangge.Com

6,字符串截取

(1)将String转化为NSString再截取
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var str = "Welecome to hangge.com"
         
var fromStr = (str as NSString).substringFromIndex(5) //ome to hangge.com
var toStr = (str as NSString).substringToIndex(5)  //Welec
var rangeStr =  (str as NSString).substringWithRange(NSMakeRange(4,1)) //c

(2)直接调用String的对应方法(推荐)

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var str = "Welecome to hangge.com"
                
let index = advance(str.startIndex, 5)
let index2 = advance(str.endIndex, -5)
var range = Range<String.Index>(start: index, end: index2)
 
var fromStr = str.substringFromIndex(index)  //ome to hangge.com
var toStr = str.substringToIndex(index2)  //Welecome to hangg
var rangeStr = str.substringWithRange(range) //ome to hangg
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