title: Overlapping accesses to "result", but modification requires exclusive access; consider copying to a local variable in xcode 10
body: <pre><code>open static func PBKDF2(_ password: String, salt: Data,
                          prf: PRFAlg, rounds: UInt32) throws -&gt; Data {
      var result = Data(count:prf.cc.digestLength)
      let passwData = password.data(using: String.Encoding.utf8)!
      let status = result.withUnsafeMutableBytes { (passwDataBytes: UnsafeMutablePointer&lt;UInt8&gt;) -&gt; CCCryptorStatus in
          return CCKeyDerivationPBKDF!(
              PBKDFAlgorithm.pbkdf2.rawValue,
              (passwData as NSData).bytes, 
              passwData.count,
              (salt as NSData).bytes, 
              salt.count,
              prf.rawValue,
              rounds,
              passwDataBytes,
              result.count)
       }
  
       guard status == noErr else { throw CCError(status) }
  
       return result
  }
  </code></pre>
  <p><code>result.withUnsafeMutableBytes</code> is giving an error in Xcode 10, In Xcode 9 it is a warning.</p>