在Swift 3.0中循環遍歷子字符串

Question

在Swift 3.0中循環一個子字符串的最佳方法是什麼？

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


    } 

以下代碼將引發錯誤：Type ClosedRange<String.Index> (aka ‘ClosedRange<String.CharacterView.Index>’) does not conform to Sequence protocol。

Answer 1

start和end是String.Index的類型，它們不能在for循環中使用;相反，您可以在以下範圍內獲得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)