title: Replace <null> string in nsdictionary
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/8477789/iterating-through-nsdictionary-for-null-value">Iterating through NSDictionary for null value</a>  </p>
  </blockquote>
  
  
  
  <p>I have a json like <a href="http://mocku.ps/wz69f" rel="nofollow noreferrer">image</a>, <strong>i want to replace all value  string to an empty string</strong>. I see <a href="https://stackoverflow.com/questions/12213822/replace-occurance-of-nsnull-in-nested-nsdictionary">that it is similar to this question</a> but all the value  have not changed.</p>