Setting up Container View Controller

Container.swift

func setupContainerView() {
        [containerVC,notchVC].forEach { (viewController) in
            self.view.addSubview(viewController.view)
        }
        heightConstraint =  containerVC.view.heightAnchor.constraint(equalToConstant: 0)
        notchBottomConstraint = notchVC.view.bottomAnchor.constraint(equalTo: self.view.bottomAnchor)
        
        NSLayoutConstraint.activate([
            containerVC.view.leadingAnchor.constraint(equalTo: self.view.leadingAnchor),
            containerVC.view.trailingAnchor.constraint(equalTo: self.view.trailingAnchor),
            containerVC.view.bottomAnchor.constraint(equalTo: self.view.bottomAnchor),
            heightConstraint,
            notchVC.view.heightAnchor.constraint(equalToConstant: 20),
            notchVC.view.leadingAnchor.constraint(equalTo: self.view.leadingAnchor),
            notchVC.view.trailingAnchor.constraint(equalTo: self.view.trailingAnchor),
            notchBottomConstraint
        ])
        
        //setup childViewController ( this view is the bottom sheet )
        [containerVC, notchVC].forEach { (viewController) in
            self.add(viewController)
        }
}