TabAndSplitView.swift

    func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
        if tabBarController.selectedViewController == viewController, let split = viewController as? UISplitViewController {
            if split.isCollapsed {
                if let navigation = split.viewControllers.first as? UINavigationController {
                    navigation.popToRootViewController(animated: true)
                }
            } else if split.displayMode == .primaryHidden {
                let mode = split.preferredDisplayMode
                split.preferredDisplayMode = mode
            }
        }
        return true
    }