iOS -在集合视图单元格周围添加边框，并在其下添加视图

class CustomCollectionViewCell: UICollectionViewCell {
    override init(frame: CGRect) {
        super.init(frame: frame)
        
        // 添加边框
        self.layer.borderWidth = 1.0
        self.layer.borderColor = UIColor.black.cgColor
        
        // 添加下方视图
        let view = UIView(frame: CGRect(x: 0, y: self.frame.size.height - 20, width: self.frame.size.width, height: 20))
        view.backgroundColor = UIColor.red
        self.addSubview(view)
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

class ViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {
    // 其他代码...
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CustomCell", for: indexPath) as! CustomCollectionViewCell
        
        // 配置单元格内容
        
        return cell
    }
    
    // 其他代码...
}

class ViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {
    // 其他代码...
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let layout = UICollectionViewFlowLayout()
        let collectionView = UICollectionView(frame: self.view.bounds, collectionViewLayout: layout)
        collectionView.dataSource = self
        collectionView.delegate = self
        collectionView.register(CustomCollectionViewCell.self, forCellWithReuseIdentifier: "CustomCell")
        
        self.view.addSubview(collectionView)
    }
    
    // 其他代码...
}