I am having an issue with Landscape mode in my iPad application.
I created a very small new project to show my issue I set UIInterfaceOrientation in the pList to UII
One of the comments on the accepted answer contained the solution to the problem for me.
There is a method you can override on UIViewController called "viewDidLayoutSubviews", I tapped into it and adjusted my containing views from there.
And since its called after "viewWillAppear" and before "viewDidAppear" the changes you make to the subviews show up as expected, no glitches.