检查屏幕UICollectionView上是否可见indexPath处的单元格

func isCellVisible(at indexPath: IndexPath, in collectionView: UICollectionView) -> Bool {
    let visibleRect = CGRect(origin: collectionView.contentOffset, size: collectionView.bounds.size)
    if let visibleCells = collectionView.visibleCells as? [UICollectionViewCell] {
        for cell in visibleCells {
            if let visibleIndexPath = collectionView.indexPath(for: cell), visibleIndexPath == indexPath {
                return true
            }
        }
    }
    return false
}