title: iPhone - Clicking on navigation bar's back button doesn't change view
body: <p>Never faced this issue before. I am using a navigation controller in my app. The app uses web services to get the data. If I go ahead 2 views and before the current view finishes loading, if I click the back button, the top bar changes as expected but the view does not.</p>
  
  <p>The view remains the same.</p>
  
  <p>This does not happen every time but most of the times I can reproduce this.</p>
  
  <p>Any idea why this happens?</p>
  
  <p>Thanks.</p>