使UICollectionView单元格在容器中居中

import UIKit

class MyViewController: UIViewController, UICollectionViewDelegateFlowLayout {
    
    private var collectionView: UICollectionView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let layout = UICollectionViewFlowLayout()
        layout.scrollDirection = .vertical
        layout.sectionInset = UIEdgeInsets(top: 10, left: 10, bottom: 10, right: 10)
        
        collectionView = UICollectionView(frame: view.bounds, collectionViewLayout: layout)
        collectionView.delegate = self
        collectionView.dataSource = self
        
        // 注册自定义的UICollectionViewCell
        
        view.addSubview(collectionView)
    }
    
    // 实现UICollectionViewDelegateFlowLayout协议中的方法，设置单元格大小
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        let containerWidth = collectionView.bounds.width - layout.sectionInset.left - layout.sectionInset.right
        let cellWidth: CGFloat = 100 // 设置单元格的宽度
        let cellHeight: CGFloat = 100 // 设置单元格的高度
        let spacing: CGFloat = 10 // 设置单元格之间的间距
        
        let numberOfCells = containerWidth / (cellWidth + spacing)
        let totalSpacing = spacing * (numberOfCells - 1)
        let cellWidthWithSpacing = (containerWidth - totalSpacing) / numberOfCells
        
        return CGSize(width: cellWidthWithSpacing, height: cellHeight)
    }
    
    // 其他UICollectionViewDataSource和UICollectionViewDelegate方法的实现...
}