title: How to reload Navigation bar
body: <p>In <code>UITableView</code> I configure <code>self.navigationItem.leftBarButtonItem</code> with a button. Now I want to reload this button to update text on this button, but it's on <code>Navigation bar</code>. I can update <code>UITableView</code> by </p>
  
  <pre><code> [self.tableView reloadData]
  </code></pre>
  
  <p>but How to update Navigation bar?</p>
  
  <p>Update: I'm NOT init the title of button, but reload it. So any init code (such as <code>self.navigationItem.leftBarButtonItem.title = @"balabala"</code>) doesn't work, because it does NOT take effect immediately.</p>