title: How to update NSMutableDictionary?
body: <p>I have an NSMutableDictionary.</p>
  
  <pre><code>NSMutableDictionary* plistDict = [[NSMutableDictionary alloc] initWithContentsOfFile:path];
  </code></pre>
  
  <p>I have to update an element in that dictionary. How i can do that?</p>