Adding / removing from a containerView

ContainerView.swift

func add(asChildViewController viewController: UIViewController) {
        
        // Add Child View Controller
        self.addChildViewController(viewController)
        
        // Add Child View as Subview
        self.drawerContainerView.addSubview(viewController.view)
//        self.view.addSubview(viewController.view)
        
        // Configure Child View
        viewController.view.frame = self.drawerContainerView.bounds
        viewController.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        
        // Notify Child View Controller
        viewController.didMove(toParentViewController: self)
    }
    
    func remove(asChildViewController viewController: UIViewController) {
        
        // Notify Child View Controller
        viewController.willMove(toParentViewController: nil)
        
        // Remove Child View From Superview
        viewController.view.removeFromSuperview()
        
        // Notify Child View Controller
        viewController.removeFromParentViewController()
    }