gistfile1.txt

class ShopCollectionViewCell: UICollectionViewCell {
    ...
    
    func collapse() {
        zeroHeightConstraint.isActive = true
    }
    
    func expand() {
        zeroHeightConstraint.isActive = false
    }
}

extension ShopViewController: UICollectionViewDelegate {
    
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        let item = indexPath.item
        
        self.selectedShop = shops[item]
        
        for i in (0..<isExpanded.count) {
            if i == item {
                // ensure always visible
                isExpanded[i] = true
            } else {
                // set all other rows to false
                isExpanded[i] = false
            }
            if let shopCollectionViewCell = collectionView.cellForItem(at: IndexPath(item: i, section: 0)) as? ShopCollectionViewCell {
                if isExpanded[i] {
                    shopCollectionViewCell.expand()
                    shopCollectionViewCell.select()
                } else {
                    shopCollectionViewCell.collapse()
                    shopCollectionViewCell.unselect()
                }
            }
        }
        
        updateButtons(selectedShop)
        
        UIView.animate(withDuration: Constants.config_shortAnimTime, animations: {
            collectionView.performBatchUpdates(nil, completion: { [weak self] _ in
                guard let self = self else { return }
                
                let minY = collectionView.contentOffset.y
                let maxY = collectionView.bounds.height + minY
                
                if let attribute = collectionView.layoutAttributesForItem(at: indexPath) {
                    let rectMinY = attribute.frame.minY
                    let rectMaxY = attribute.frame.maxY + self.PADDING
                    
                    if rectMinY < minY {
                        self.ensureSelectedRowViewStaysAtTheTop()
                    } else if rectMaxY > maxY {
                        let cgPoint = CGPoint(
                            x: collectionView.contentOffset.x,
                            y: collectionView.contentOffset.y + (rectMaxY - maxY)
                        )
                        
                        collectionView.setContentOffset(cgPoint, animated: true)
                    }
                }
            })
        })
    }