Camel case to snake case in Swift

SnakeCase.swift

extension String {

  func snakeCased() -> String? {
    let pattern = "([a-z0-9])([A-Z])"

    let regex = try? NSRegularExpression(pattern: pattern, options: [])
    let range = NSRange(location: 0, length: self.characters.count)
    return regex?.stringByReplacingMatches(in: self, options: [], range: range, withTemplate: "$1_$2").lowercased()
  }
}

In case anyone needs it, I updated it for Swift 4.2 version. Thanks!
https://gist.github.com/dmsl1805/ad9a14b127d0409cf9621dc13d237457

Thank you.

Thanks!