class ChildCollectionViewController: UICollectionViewController {
    override func viewDidLoad() {
        super.viewDidLoad()

        self.collectionView!.translatesAutoresizingMaskIntoConstraints = false
        if #available(iOS 11, *) {
            self.view.safeAreaLayoutGuide.leftAnchor.constraint(equalTo: collectionView!.leftAnchor).isActive = true
            self.view.safeAreaLayoutGuide.topAnchor.constraint(equalTo: collectionView!.topAnchor).isActive = true
            self.view.safeAreaLayoutGuide.rightAnchor.constraint(equalTo: collectionView!.rightAnchor).isActive = true
            self.view.safeAreaLayoutGuide.bottomAnchor.constraint(equalTo: collectionView!.bottomAnchor).isActive = true
        } else {
            self.view.leftAnchor.constraint(equalTo: collectionView!.leftAnchor).isActive = true
            self.topLayoutGuide.topAnchor.constraint(equalTo: collectionView!.topAnchor).isActive = true
            self.view.rightAnchor.constraint(equalTo: collectionView!.rightAnchor).isActive = true
            self.bottomLayoutGuide.bottomAnchor.constraint(equalTo: collectionView!.bottomAnchor).isActive = true
        }
    }
}