title: Black screen when present new controller and dismiss current controller
body: <p>Currently I have 3 controllers, A, B and C. I click one button in <code>AController</code> and  present <code>BController</code>, then I call one api in <code>BController</code>, if it is successful, I wanner go to <code>CController</code>, but I want to dismiss <code>BController</code> at the same time. Then I call another api in <code>CController</code> successfully, when I dismiss <code>CController</code>, I hope the screen will go back to <code>Acontroller</code>. All the three controllers are not in navigation controller stack. </p>
  
  <p>My implementation: </p>
  
  <p>In <code>BController</code>, call <code>presentViewController:(CController)</code> method and <code>dismissViewController:(self)</code>, but I failed, the screen is nothing with black color, hope some guys can help me solve this issue. </p>
  
  <p>Thanks!</p>