如何居中对齐collectionView单元格？

class MyViewController: UIViewController, UICollectionViewDelegateFlowLayout {
    
    // ...
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        let cellWidth = collectionView.bounds.width // 单元格的宽度等于collectionView的宽度
        let cellHeight = collectionView.bounds.height // 单元格的高度等于collectionView的高度
        return CGSize(width: cellWidth, height: cellHeight)
    }
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
        let leftInset = (collectionView.bounds.width - collectionViewLayout.collectionViewContentSize.width) / 2 // 左内边距
        let rightInset = leftInset // 右内边距等于左内边距
        return UIEdgeInsets(top: 0, left: leftInset, bottom: 0, right: rightInset)
    }
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        return 0 // 行间距为0，确保单元格在垂直方向上居中对齐
    }
    
    // ...
    
}