title: Swift-3 error: '-[_SwiftValue unsignedIntegerValue]: unrecognized selector
body: <p>Following code was perfectly worked with old swift. This is an extension of String</p>
  
  <pre><code>func stringByConvertingHTML() -&gt; String {
      let newString = replacingOccurrences(of: "\n", with: "&lt;br&gt;")
      if let encodedData = newString.data(using: String.Encoding.utf8) {
          let attributedOptions : [String: AnyObject] = [
              NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType as AnyObject,
              NSCharacterEncodingDocumentAttribute: String.Encoding.utf8 as AnyObject
          ]
          do {
              let attributedString = try NSAttributedString(data: encodedData, options: attributedOptions, documentAttributes: nil) //Crash here
              return attributedString.string
          } catch {
              return self
          }
      }
      return self
  }
  </code></pre>
  
  <p>But in swift 3 it crashes saying </p>
  
  <blockquote>
    <p>*** Terminating app due to uncaught exception
    'NSInvalidArgumentException', reason: '-[_SwiftValue
    unsignedIntegerValue]: unrecognized selector sent to instance
    0x6080002565f0'</p>
  </blockquote>
  
  <p>Anyone please suggest me what need to do?</p>