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

1 2	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

1 2	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