String+MD5.swift

import CommonCrypto

extension String {
  var md5: String? {
    guard let data = self.data(using: .utf8) else { return nil }

    let hash = data.withUnsafeBytes { (bytes: UnsafePointer<Data>) -> [UInt8] in
      var hash: [UInt8] = [UInt8](repeating: 0, count: Int(CC_MD5_DIGEST_LENGTH))
      CC_MD5(bytes, CC_LONG(data.count), &hash)
      return hash
    }

    return hash.map { String(format: "%02x", $0) }.joined()
  }
}