如何在UICollectionView之上呈现一个UIViewController？

class CustomCollectionViewCell: UICollectionViewCell {
    var viewController: UIViewController? {
        didSet {
            if let viewController = viewController {
                // 将UIViewController的视图添加到容器视图中
                viewController.view.frame = contentView.bounds
                contentView.addSubview(viewController.view)
                viewController.didMove(toParent: self)
            } else {
                // 移除之前的UIViewController
                for subview in contentView.subviews {
                    subview.removeFromSuperview()
                }
            }
        }
    }
    
    override func prepareForReuse() {
        super.prepareForReuse()
        viewController = nil
    }
}

class ViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
    let collectionView: UICollectionView
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 初始化UICollectionView
        let layout = UICollectionViewFlowLayout()
        collectionView = UICollectionView(frame: view.bounds, collectionViewLayout: layout)
        collectionView.dataSource = self
        collectionView.delegate = self
        collectionView.register(CustomCollectionViewCell.self, forCellWithReuseIdentifier: "Cell")
        view.addSubview(collectionView)
    }
    
    // UICollectionViewDataSource方法
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 10
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as! CustomCollectionViewCell
        
        // 创建并设置对应的UIViewController
        let viewController = UIViewController()
        viewController.view.backgroundColor = .red
        cell.viewController = viewController
        
        return cell
    }
    
    // UICollectionViewDelegateFlowLayout方法
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize(width: collectionView.bounds.width, height: 200)
    }
}