private let reuseIdentifier = "MyCollectionViewCell"

struct CarBrand {
    var brandName: String
    var imageView: UIImageView
}

class MyCollectionViewController: UICollectionViewController {

    fileprivate let sectionInsets = UIEdgeInsets(top: 50.0, left: 20.0, bottom: 50.0, right: 20.0)
    fileprivate var cells = [CarBrand]()

    fileprivate let heigthForBrandLabel:CGFloat = 10
    fileprivate let itemsPerRow: CGFloat = 2

    override func viewDidLoad() {
        super.viewDidLoad()
        cells = fillCollectionViewData()
        collectionView?.reloadData()
        //self.collectionView?.reloadData()
        // Uncomment the following line to preserve selection between presentations
        // self.clearsSelectionOnViewWillAppear = false

        // Register cell classes
        //self.collectionView!.register(MyCollectionViewCell.self, forCellWithReuseIdentifier: reuseIdentifier)

        // Do any additional setup after loading the view.
    }


    // MARK: UICollectionViewDelegate

    /*
    // Uncomment this method to specify if the specified item should be highlighted during tracking
    override func collectionView(_ collectionView: UICollectionView, shouldHighlightItemAt indexPath: IndexPath) -> Bool {
        return true
    }
    */

    /*
    // Uncomment this method to specify if the specified item should be selected
    override func collectionView(_ collectionView: UICollectionView, shouldSelectItemAt indexPath: IndexPath) -> Bool {
        return true
    }
    */

    /*
    // Uncomment these methods to specify if an action menu should be displayed for the specified item, and react to actions performed on the item
    override func collectionView(_ collectionView: UICollectionView, shouldShowMenuForItemAt indexPath: IndexPath) -> Bool {
        return false
    }

    override func collectionView(_ collectionView: UICollectionView, canPerformAction action: Selector, forItemAt indexPath: IndexPath, withSender sender: Any?) -> Bool {
        return false
    }

    override func collectionView(_ collectionView: UICollectionView, performAction action: Selector, forItemAt indexPath: IndexPath, withSender sender: Any?) {

    }
    */

}
// MARK: Private functions

extension MyCollectionViewController {
    fileprivate func fillCollectionViewData() -> [CarBrand] {
        var newCells = [CarBrand]()

        for _ in 0..<6 {
            let imageView = UIImageView(image: UIImage(named: "bitcoin-gold.png"))
            let car = CarBrand(brandName: "default", imageView: imageView)
            newCells.append(car)
        }
        for i in 0..<6 {
            switch i {
            case 0:
                newCells[i].brandName = "BMW"
                newCells[i].imageView.image = UIImage(named: "0.png")
            case 1:
                newCells[i].brandName = "Audi"
                newCells[i].imageView.image = UIImage(named: "1.jpg")
            case 2:
                newCells[i].brandName = "Mercedes Benz"
                newCells[i].imageView.image = UIImage(named: "2.jpg")
            case 3:
                newCells[i].brandName = "Volkswagen"
                newCells[i].imageView.image = UIImage(named: "3.jpg")
            case 4:
                newCells[i].brandName = "Skoda"
                newCells[i].imageView.image = UIImage(named: "4.png")
            case 5:
                newCells[i].brandName = "Fiat"
                newCells[i].imageView.image = UIImage(named: "5.jpg")
            default:
                break
            }
        }
        return newCells
    }
}
// MARK: UICollectionViewDataSource
extension MyCollectionViewController {
    override func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }


    override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        // #warning Incomplete implementation, return the number of items
        return cells.count
    }

    override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let car = cells[indexPath.row]
        guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath) as? MyCollectionViewCell else {
            fatalError("The dequeued cell is not an instance of \(reuseIdentifier).")
        }
        cell.brandNameLabel.text = car.brandName
        cell.brandImageView.image = car.imageView.image
        return cell
    }
}

// MARK: UICollectionViewDelegateFlowLayout

extension MyCollectionViewController : UICollectionViewDelegateFlowLayout {
    func collectionView(_ collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        sizeForItemAt indexPath: IndexPath) -> CGSize {

        let paddingSpace = sectionInsets.left * (itemsPerRow + 1)
        let availableWidth = view.frame.width - paddingSpace
        let widthPerItem = availableWidth / itemsPerRow
        let heigthPerItem = widthPerItem + heigthForBrandLabel

        return CGSize(width: widthPerItem, height: heigthPerItem)
    }

    func collectionView(_ collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        insetForSectionAt section: Int) -> UIEdgeInsets {
        return sectionInsets
    }

    // 4
    func collectionView(_ collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        return sectionInsets.left
    }
}