title: incompatible pointer types assigning to 'AAViewController *__strong' from 'UIView *const_strong'
body: <p>Checking a controller in navigation controller stack, but assigning a controller value get a warning
   'incompatible pointer types assigning to 'AAViewController *__strong' from 'UIView *const_strong''</p>
  
  <p>AAViewController *controller;</p>
  
  <pre><code>for(UIView *view in self.navigationController.viewControllers)
  {            
       if([view isKindOfClass:[AAViewController class]])
       {
           controller = view;
           break;
       }
  }
  </code></pre>
  
  <p>i got a error in controller = view 
  thanks in advance</p>