title: changing to a different view with animation on rotation
body: <p>This ought to be simple, but oddly I haven't found a good answer for it.</p>
  
  <p>Let's say I'm trying to make an app that is just like apple's calculator, which upon rotation, doesn't just move buttons around, but switches to an entirely new view... what are the simplest possible mechanics of that?</p>
  
  <p>I'd really like to work from here:</p>
  
  <p><a href="http://content.screencast.com/users/iamafractal/folders/Jing/media/0a8469d1-5d3e-4d4b-ba71-9a0ed085650f/00001158.png" rel="nofollow noreferrer">Calculator Storyboards http://content.screencast.com/users/iamafractal/folders/Jing/media/0a8469d1-5d3e-4d4b-ba71-9a0ed085650f/00001158.png</a></p>
  
  <p>I vaguely understand that I need a rotation related method in a view controller, and some kind of delegate, and maybe another view controller for the other view, but I'd like it if the two view controllers shared as much code as possible... so is there a view controller class and then the other vc is a daughter of that just with the extra methods to cover the additional buttons and functionality? so how would that look in code?</p>