title: UISplitViewController Cannot Change the Master View Controller?
body: <p>I am trying to change the master view controller (that appears in the popover in portrait, and on the left side in landscape) in a UISplitViewController. I'd like to switch between the master view controller being one of two different UIViewControllers (depending on an action taken elsewhere in my application).</p>
  
  <p>I am using the following:</p>
  
  <blockquote>
    <p>mySplitViewController.viewControllers = [NSArray arrayWithObjects:newMasterController, detailController, nil];</p>
  </blockquote>
  
  <p>This correctly changes the master viewcontroller as you would expect in landscape mode. However it does <strong>not</strong> seem to change the viewcontroller used for the popover in portrait mode.</p>
  
  <p>I notice that the barbuttonitem to show this master view controller is just calling showMasterInPopover: on the splitviewcontroller, and so would expect it to work in portrait mode as well, but it does not. </p>
  
  <p>In fact, I can set the master view controller, see the <em>new</em> viewController correctly in landscape mode, rotate <em>back</em> to portrait, and the viewcontroller used in the popover is <em>still</em> the old one.</p>
  
  <p>Is this a bug?</p>