title: How to get interfaceOrientation property set correctly in view controller hierarchy?
body: <p>I have a custom view controller hierarchy. 
  A sub view controller is added, to a custom parent view controller simply as a subview. The parent view controller also calls the sub view controller's <code>-[willRotateToInterfaceOrientation:duration:]</code> and <code>-[didRotateFromInterfaceOrientation:]</code> methods at the correct time.</p>
  
  <p>Everything seems to work as it should, but for some reason, the <code>interfaceOrientation</code> property is not set correctly, it is always <code>UIInterfaceOrientationPortrait</code>. </p>
  
  <p>How do I get the sub view controller to have the correct value in <code>interfaceOrientation</code> when I rotate to landscape?</p>