Swift - 字串（String）用法詳解

下面對String常用的屬性和方法做個總結

1，判斷是否為空：isEmpty

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var str:String if str.isEmpty{ }

2，獲取字元數量：countElements

1 2	let str = "hangge.com" println("\(countElements(str))個字元")

3，檢查字串是否有特定字首/字尾：hasPrefix/hasSuffix

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

4，還可以用“\()”在字串裡包裹變數，常量

1 2	let name = "hangge.com" let msg = "歡迎來到 \(name)"

5，大小寫轉換：

通過字串的uppercaseString、lowercaseString、capitalizedString屬性來訪問一個字串的大寫/小寫/首字母大寫

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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，字串擷取

（1）將String轉化為NSString再擷取

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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）直接呼叫String的對應方法（推薦）

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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