在Swift 3.0中循环遍历子串

Question

在Swift 3.0中循环子字符串的最佳方法是什么？

var start = s.startIndex
var end = s.index(s.endIndex, offsetBy: -10)
   for i in start...end {


   }

以下代码会引发错误：Type ClosedRange<String.Index> (aka ‘ClosedRange<String.CharacterView.Index>’) does not conform to Sequence protocol。

Answer 1

start和end是String.Index的类型，它们不能用于for循环;相反，您可以在以下范围内获得substring：

var start = s.startIndex
var end = s.index(s.endIndex, offsetBy: -10)
let range = Range(uncheckedBounds: (lower: start, upper: end))
let subString = s.substring(with: range)