         
         currentController.removeFromParentViewController()
         
-        self.addChildViewController(controller)
+        addChildViewController(controller)
         controller.beginAppearanceTransition(true, animated:true)
         currentController.beginAppearanceTransition(false, animated:true)
         

            return
        }
        
        self.addChildViewController(controller)
        
        controller.beginAppearanceTransition(
            true,

            return
        }
        
        addChildViewController(controller)
        
        controller.beginAppearanceTransition(
            true,
