如何创建打开/关闭collectionView分区

let layout = UICollectionViewFlowLayout()
let collectionView = UICollectionView(frame: CGRect.zero, collectionViewLayout: layout)

func numberOfSections(in collectionView: UICollectionView) -> Int {
    // 返回分区的数量
    return 1
}

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    // 返回每个分区中的项数
    return dataArray.count
}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    // 返回每个项的单元格
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CellIdentifier", for: indexPath) as! CustomCell
    cell.textLabel.text = dataArray[indexPath.row]
    return cell
}

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    // 用户选择了某个项时的操作
    // 可以在这里打开或关闭分区
    collectionView.performBatchUpdates({
        if isSectionOpen {
            // 关闭分区
            collectionView.deleteItems(at: indexPathsForSection(indexPath.section))
        } else {
            // 打开分区
            collectionView.insertItems(at: indexPathsForSection(indexPath.section))
        }
        isSectionOpen = !isSectionOpen
    }, completion: nil)
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    // 返回每个项的大小
    if isSectionOpen && indexPath.section == openSectionIndex {
        // 打开分区时，返回打开状态下的项的大小
        return CGSize(width: 100, height: 100)
    } else {
        // 关闭分区时，返回关闭状态下的项的大小
        return CGSize(width: 50, height: 50)
    }
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
    // 返回分区的内边距
    if isSectionOpen && section == openSectionIndex {
        // 打开分区时，返回打开状态下的内边距
        return UIEdgeInsets(top: 10, left: 10, bottom: 10, right: 10)
    } else {
        // 关闭分区时，返回关闭状态下的内边距
        return UIEdgeInsets.zero
    }
}

func indexPathsForSection(_ section: Int) -> [IndexPath] {
    // 返回指定分区的所有项的IndexPath
    var indexPaths = [IndexPath]()
    for row in 0..<dataArray.count {
        indexPaths.append(IndexPath(row: row, section: section))
    }
    return indexPaths
}