iOS: 在Swift中優雅的實現Substring

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在Swift中，當我們想要截取某個字串時，方法如下：

let carNumber = "滬A12345"let startIndex = advance(userCar.carPlateNumber.startIndex, 0)let endIndex = advance(startIndex, 1)let range = startIndex..<endIndexprintln(carNumber[range]) // 輸出滬

呃，好懷念substring方法啊，那我們就自己實現一個吧。

extension String {    subscript (r: Range<Int>) -> String {        get {            let startIndex = advance(self.startIndex, r.startIndex)            let endIndex = advance(startIndex, r.endIndex - r.startIndex)                        return self[Range(start: startIndex, end: endIndex)]        }    }}

調用很簡單，樣本如下：

var s = "Hello, playground"println(s[0...5]) // ==> "Hello,"println(s[0..<5]) // ==> "Hello"

感謝Rob Napier http://stackoverflow.com/questions/24044851/how-do-you-use-string-substringwithrange-or-how-do-ranges-work-in-swift

iOS: 在Swift中優雅的實現Substring