Swift rangeOfString 索引 0 或 1

Question

我有一个名称数组，想从下面的数组中过滤掉第一个或第二个字母为“E”的名称

var userNames = ["John","Tom","Ed","Ben","Albert"]

输出应该是["Ed","Ben"]。 Albert 不应包括在内，因为该位置不是来自第一或第二

let filteredNames = userName.filter { (inputStr) -> Bool in

     if let inputRang =  inputStr.range(of: "e", options: .caseInsensitive, range: nil, locale: nil)
     {
        //How do I check the position 0 or 1 here

        return true
    }
    return false
}

Answer 1

@Eendje 发布了一个很好且有效的解决方案来实现您的目标，但要回答您的问题直接问题:你必须计算距离从字符串初始索引(inputStr.startIndex)到位置找到子字符串的位置(inputRange.lowerBound):

let filteredNames = userNames.filter { (inputStr) -> Bool in
    if let inputRange = inputStr.range(of: "e", options: .caseInsensitive) {
        if inputStr.distance(from: inputStr.startIndex, to: inputRange.lowerBound) <= 1 {
            return true
        }
    }
    return false
}

另一种选择是限制搜索范围:

let filteredNames = userNames.filter { (inputStr) -> Bool in
    let range = inputStr.startIndex ..< inputStr.index(inputStr.startIndex, offsetBy: 2)
    return inputStr.range(of: "e", options: .caseInsensitive, range: range) != nil
}