title: Fix warning: cannot pair a synthesized setter/getter with a user defined setter/getter
body: <p>I use in my application <code>QHTTPOperation.{h/m}</code> found <a href="http://developer.apple.com/library/ios/#samplecode/MVCNetworking/Listings/Networking_QHTTPOperation_m.html" rel="nofollow">here</a> all work properly but I got 8 warnings as follow:</p>
  
  <blockquote>
    <p>Writable atomic property 'acceptableStatusCodes' cannot pair a
    synthesized setter/getter with a user defined setter/getter</p>
    
    <p>Writable atomic property 'acceptableContentTypes' cannot pair a
    synthesized setter/getter with a user defined setter/getter</p>
    
    <p>Writable atomic property 'authenticationDelegate' cannot pair a
    synthesized setter/getter with a user defined setter/getter</p>
    
    <p>...</p>
  </blockquote>
  
  <p>I am asking because I have noticed that in the project of the above link there is no Warnings related to <code>QHTTPOperation.{h/m}.</code></p>
  
  <p>Any idea?</p>
  
  <p>Thanks</p>