title: UITableView contentOffSet is not working properly
body: <p>In <code>viewWillAppear</code>, I have added <code>UISearchBar</code> as my headerview of <code>UITableView</code>. When view loads, I hides <code>UISearchbar</code> under <code>UINavigationBar</code> using contentOffSet of <code>UITableView</code>. When user pull down the tableview the searchbar gets displayed.</p>
  
  <p>After adding headerview I hides it using below code.</p>
  
  <pre><code>self.tableView.contentOffset = CGPointMake(0, 40); //My searhbar height is 40
  </code></pre>
  
  <p>But at times <code>contentOffSet</code> is not hiding headerview. What can be the mistake.</p>