func application(_ application: UIApplication, supportedInterfaceOrientationsFor window: UIWindow?) -> UIInterfaceOrientationMask {
    if let navigationController = self.window?.rootViewController as? UINavigationController {
        if navigationController.visibleViewController is DetailsTableViewController {
            return UIInterfaceOrientationMask.all
        } else {
            return UIInterfaceOrientationMask.portrait
        }
    }
    return UIInterfaceOrientationMask.portrait
}