页眉部分未以编程方式显示在集合视图中

import UIKit

class CustomCollectionViewLayout: UICollectionViewFlowLayout {
    override func prepare() {
        super.prepare()
        
        // 设置页眉部分的大小和位置
        if let headerSize = self.collectionView?.bounds.size {
            let headerAttributes = UICollectionViewLayoutAttributes(forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, with: IndexPath(item: 0, section: 0))
            headerAttributes.frame = CGRect(x: 0, y: 0, width: headerSize.width, height: 50) // 自定义页眉高度为50
            self.headerReferenceSize = headerAttributes.frame.size
            self.sectionInset = UIEdgeInsets(top: headerAttributes.frame.height, left: 0, bottom: 0, right: 0)
        }
    }
    
    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        var layoutAttributes = super.layoutAttributesForElements(in: rect)
        
        // 添加页眉部分的布局属性到数组中
        if let headerAttributes = layoutAttributesForSupplementaryView(ofKind: UICollectionView.elementKindSectionHeader, at: IndexPath(item: 0, section: 0)) {
            layoutAttributes?.append(headerAttributes)
        }
        
        return layoutAttributes
    }
    
    override func layoutAttributesForSupplementaryView(ofKind elementKind: String, at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
        if elementKind == UICollectionView.elementKindSectionHeader {
            return UICollectionViewLayoutAttributes(forSupplementaryViewOfKind: elementKind, with: indexPath)
        }
        
        return super.layoutAttributesForSupplementaryView(ofKind: elementKind, at: indexPath)
    }
}

class ViewController: UIViewController, UICollectionViewDataSource {
    var collectionView: UICollectionView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let layout = CustomCollectionViewLayout()
        collectionView = UICollectionView(frame: view.bounds, collectionViewLayout: layout)
        collectionView.dataSource = self
        collectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: "Cell")
        collectionView.register(UICollectionReusableView.self, forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: "Header")
        view.addSubview(collectionView)
    }
    
    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }
    
    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)
        cell.backgroundColor = UIColor.blue
        return cell
    }
    
    func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
        let header = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "Header", for: indexPath)
        header.backgroundColor = UIColor.red
        return header
    }
}