title: How to get HTTP protocol version from a given NSHTTPURLResponse?
body: <p>From <code>NSHTTPURLResponse</code> documentation, I did not find a way to get the <code>HTTP</code> version <code>(i.e. "HTTP/1.1" or "HTTP/1.0")</code>. </p>
  
  <p><code>HTTP</code> header fields are available through all Header Fields property, however the <code>HTTP</code> protocol version is not given inside the header fields as it is not an <code>HTTP</code> header. </p>
  
  <p><strong>Note:</strong> init, <code>NSHTTPURLResponse</code> initializer 
  <code>(initWithURL:statusCode:HTTPVersion:headerFields:)</code> does require the <code>HTTPVersion</code> as an input, so theoretically it may have been saved there. </p>
  
  <p>However, I couldn't find a property or method to get the <code>HTTPVersion</code> from a given response, for example a response returned from an NSURLSessionDataTask.</p>