Swift开发如何获取字符串中重复子串对应的不同NSRange区间

云上老周

2026-9-26

实现思路

你现有代码的问题是每次调用range(of:)都从文本起始位置搜索，所以重复文本只会返回第一个匹配的区间。你可以通过两步实现按数组顺序匹配重复文本的不同区间：先预先缓存所有目标文本的全部出现位置，再遍历原数组按顺序取对应位置即可。

完整代码

// 1. 预处理缓存所有目标文本的全部出现区间
var rangeCache: [String: [NSRange]] = [:]
let validTargetTexts = textsToChange.compactMap { $0.result != nil ? $0.text : nil }
let fullNSString = textFieldText as NSString

for text in Set(validTargetTexts) {
    var allRanges: [NSRange] = []
    var searchRange = NSRange(location: 0, length: fullNSString.length)
    while searchRange.location <= fullNSString.length {
        let matchedRange = fullNSString.range(of: text, range: searchRange)
        guard matchedRange.location != NSNotFound else { break }
        allRanges.append(matchedRange)
        // 下一轮搜索从当前匹配的结束位置开始
        searchRange.location = matchedRange.upperBound
        searchRange.length = fullNSString.length - searchRange.location
    }
    rangeCache[text] = allRanges
}

// 2. 遍历原数组按顺序取对应区间
var textIndexCounter: [String: Int] = [:]
let ranges: [NSRange] = textsToChange.compactMap { item in
    guard item.result != nil else { return nil }
    let targetText = item.text
    let currentTakeIndex = textIndexCounter[targetText, default: 0]
    guard let textRanges = rangeCache[targetText], currentTakeIndex < textRanges.count else {
        return nil
    }
    let resultRange = textRanges[currentTakeIndex]
    textIndexCounter[targetText] = currentTakeIndex + 1
    return resultRange
}