private var expandedCell: ExpandableCell?
private var isStatusBarHidden = false

override var prefersStatusBarHidden: Bool {
    return isStatusBarHidden
}

// …

override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    if collectionView.contentOffset.y < 0 ||
        collectionView.contentOffset.y > collectionView.contentSize.height - collectionView.frame.height {
        return
    }

    if let selectedCell = expandedCell {
        isStatusBarHidden = false

        selectedCell.collapse()

        collectionView.isScrollEnabled = true

        expandedCell = nil
    } else {
        isStatusBarHidden = true

        collectionView.isScrollEnabled = false

        let selectedCell = collectionView.cellForItem(at: indexPath)! as! ExpandableCell
        selectedCell.expand(in: collectionView)

        expandedCell = selectedCell
    }

    self.setNeedsStatusBarAppearanceUpdate()
}