title: animate picker view over tab bar like keyboard
body: <p>I animate a custom view with a picker subview like how a keyboard appears when activating a UITextField.</p>
  
  <p>Currently I do it by adding my custom view as a subview to the app's UIWindow.  If I add the the custom view as a subview to the current tab bar view controller's view, the tab bar will cover the picker.  Is there a way to animate the custom view as a subview of the current view controller without having the tab bar covering the custom view?  What view does the keyboard come up on?</p>