title: add a view under tabbar in storyboard
body: <p>I'm wondering if there's a way (preferably an easy one) to add a view under the tab bar, like shown on the attached picture, so that it stays there when I switch between tabs and when new view controllers are pushed/popped on each tab.</p>
  
  <p>I have subclassed UITabBarController as "MainTabController" and set is as the custom class for the Main Tab Bar Controller Scene in my storyboard. Then in MainTabController's viewDidLoad I move the tabBar up and add the red subview. So far so good, but the main view area size is still like it was before, with the tab bar at the bottom, so now the last few elements of the table stay below the tab bar.</p>
  
  <p>I would very much like to avoid adjusting the frame size for each and every controller I push into either of the tabs, so I hope that there's a simpler solution that I'm not aware of.</p>
  
  <p><img src="https://i.stack.imgur.com/gRkfj.png" alt="what it should look like"></p>