title: Content of UIPopoverController slides out of view when Keyboard is dispatched
body: <p>I have an iPad app who's login screen looks like this (top of image clipped because of sensitive info):
  <img src="https://i.stack.imgur.com/CT0EB.png" alt="enter image description here"></p>
  
  <p>When the user taps "Log In" button I load a UIPopoverController with some buttons:</p>
  
  <p><img src="https://i.stack.imgur.com/B56ki.png" alt="enter image description here"></p>
  
  <p>When the user taps "Email" button, I release the first popover and create another one with two text fields:</p>
  
  <p><img src="https://i.stack.imgur.com/hBP9n.png" alt="enter image description here"></p>
  
  <p>Looking good so far, but when the user selects the text field in order to enter text, both of the UITextField controls slide off of the top of the PopoverController, like this:</p>
  
  <p><img src="https://i.stack.imgur.com/MmSQh.png" alt="enter image description here"></p>
  
  <p>I am using storyboards/segues for these popover controllers, with a little hand coded stuff to handle device rotations. I am using Autolayout and both of the UITextFields are pinned to the SuperView Top and Leading edge. That is all. </p>
  
  <p>If I move the buttons up more towards the top of the screen (out of the way of the keyboard), this behavior is still present. </p>
  
  <p>What is triggering this and where can I override its behavior?</p>