Swift extract regex matches

Question

I want to extract substrings from a string that match a regex pattern.

So I\'m looking for something like this:

func matchesForRegexInText(regex: St         


        

Answer 1

Even if the matchesInString() method takes a String as the first argument, it works internally with NSString, and the range parameter must be given using the NSString length and not as the Swift string length. Otherwise it will fail for "extended grapheme clusters" such as "flags".

As of Swift 4 (Xcode 9), the Swift standard library provides functions to convert between Range and NSRange.

func matches(for regex: String, in text: String) -> [String] {

    do {
        let regex = try NSRegularExpression(pattern: regex)
        let results = regex.matches(in: text,
                                    range: NSRange(text.startIndex..., in: text))
        return results.map {
            String(text[Range($0.range, in: text)!])
        }
    } catch let error {
        print("invalid regex: \(error.localizedDescription)")
        return []
    }
}

Example:

let string = "