parse host file using swift regex

SwiftHostFileParsing.swift

func captureGroups(withRegex pattern: String, with hosts:String) -> [String] {    
    var matches : [String] = []
    var regex: NSRegularExpression
    do {
        regex = try NSRegularExpression(pattern: pattern, options: [.caseInsensitive, .anchorsMatchLines])
    } catch {
        return matches
    }
    regex.enumerateMatches(in: hosts, options: [], range: NSRange(location: 0, length: hosts.characters.count)) { (result: NSTextCheckingResult?, flags: NSRegularExpression.MatchingFlags, _) in
      if let range = result?.rangeAt(1) {
        matches.append((hosts as NSString).substring(with: range))
      }
      if let range = result?.rangeAt(3) {
        matches.append((hosts as NSString).substring(with: range))
      }
    }
    return matches
}


let url = Bundle.main.url(forResource: "hosts", withExtension: "")
do {
  if let path = url?.path {
    let hosts = try String(contentsOfFile: path, encoding: .utf8)
    let groups = captureGroups(withRegex: "^(?!#)([^\\s]*)(\\s+)(.*)$", with:hosts)
    print(groups)
  }
print(hosts)
} catch(let er) {
  print(er)
}