title: Set default handler for "unrecognized selector" exception
body: <p>In Objective-C, is there a way to set a default hander to avoid <code>unrecognizedselector</code> exception ? I want to make the <code>NSNULL</code> and <code>NSNumber</code> to response all the methods in <code>NSString</code>.</p>
  
  <p>Thanks! </p>