在Swift中,当我们想要截取某个字符串时,方法如下:

let carNumber = "沪A12345"
let startIndex = advance(userCar.carPlateNumber.startIndex, 0)
let endIndex = advance(startIndex, 1)
let range = startIndex..<endIndex
println(carNumber[range]) // 输出沪

呃,好怀念substring方法啊,那我们就自己实现一个吧。

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)]
}
}
}

调用很简单,示例如下:

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

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

05-11 14:05