title: How to pop to root after double tapping a tab bar item?
body: <p>Normally when a <code>UINavigationController</code> is placed in a <code>UITabBarController</code> the navigation controller pops to root with the respective tab it is in is double tapped. How do I achieve the same effect with a <code>UISplitViewController</code> is between the tab bar controller and the navigation controller? Ideally it would recurse through the view controller's child view controllers and calling <code>popToRootViewController</code> on all navigation controllers that it finds. Do I have to add my own gesture recognizer to the tab bar since it doesn't look like there is a hook for knowing when a user has double tapped a tab?</p>