Regex.swift

extension String {

    func match(regex pattern: String) -> [String] {
        do {
            let text = self
            let regex = try NSRegularExpression(pattern: pattern)
            let matches = regex.matches(in: text,
                                        range: NSRange(text.startIndex..., in: text))
            return matches.flatMap { match in
                (0..<match.numberOfRanges).map {
                    let rangeBounds = match.range(at: $0)
                    guard let range = Range(rangeBounds, in: text) else {
                        return ""
                    }
                    return String(text[range])
                }
            }
        } catch {
            return []
        }
    }
}


"202107TE".match(regex: #"^\d{6}|(?<=[A-Z])\w\dF?$"#)
"202107XIF".match(regex: #"^\d{6}|(?<=[A-Z])\w\dF?$"#)
"202012CN".match(regex: #"^\d{6}|(?<=[A-Z])\w\dF?$"#)
"202101G2F".match(regex: #"^\d{6}|(?<=[A-Z])\w\dF?$"#)
"202107WMTN1F".match(regex: #"^\d{6}|(?<=[A-Z])\w\dF?$"#)