Infinite Scroll in collectionView swift programmatically

i want to infinite scrolling 10 images in collectionView programmatically of swift. the image came from web by json according to my choice. i have been unable to scrolling 20 image in a times. here is my code

import Foundation


import UIKit

let categoryCellid = "categoryCellid"


class ProductByCategoryCollectionView: UICollectionViewController, UICollectionViewDelegateFlowLayout {

    var headercellId = "headercellId"


    var callCategoryObject = [Product]()


    func getPropductListByCategory(){

        // has api code, that was well
    }




    override func viewDidLoad() {
        super.viewDidLoad()



        self.getPropductListByCategory()


        collectionView?.backgroundColor = .white

        navigationItem.title = "Product"
        navigationItem.backBarButtonItem = UIBarButtonItem(title: "Back", style: .plain, target: nil, action: nil)
        navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Sort By", style: .plain, target: nil, action: nil)



        self.setupHeaderView()

        collectionView?.register(ProductByCategoryCollectionViewCell.self, forCellWithReuseIdentifier: categoryCellid)
    }



    func showCategoryDetailSegue() {

        let detailcontroller = UIViewController()
        navigationController?.pushViewController(detailcontroller, animated: true)
    }



    func sortBtnTarget() {

    }



    func filterBtnTarget() {

    }

    let dividedLine: UIView = {
        let view = UIView()

        view.backgroundColor = UIColor(white: 0.4, alpha: 0.4)
        return view

    }()

    let totalItemLabel: UILabel = {
        let label = UILabel()

        label.text = ""
        label.textAlignment = .center
        label.font = UIFont.systemFont(ofSize: 15)
        label.backgroundColor = UIColor.white

        return label
    }()



    let dividerLineView: UIView = {
        let view = UIView()
        view.backgroundColor = UIColor.white

        return view
    }()



    func setupHeaderView(){


        view.backgroundColor = UIColor(white: 0.4, alpha: 0.4)


        dividedLine.frame = CGRect(x: 0, y: 95, width: view.frame.width, height: 1)
        totalItemLabel.frame = CGRect(x: 0, y: 55, width: view.frame.width, height: 40)

        view.addSubview(totalItemLabel)

        view.addSubview(dividedLine)





    }



    override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {


        return callCategoryObject.count
    }

    override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {


        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: categoryCellid, for: indexPath) as! ProductByCategoryCollectionViewCell
        cell.callProductObject4Cell = callCategoryObject[indexPath.item]



        return cell
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize(width: 172, height: 300)
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
        return UIEdgeInsetsMake(32, 10, 0, 10)
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
        return 0
    }

    override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {


        let layout = UICollectionViewFlowLayout()
        layout.scrollDirection = .horizontal
        let controller1 = DetailsController(collectionViewLayout: layout)
        navigationController?.pushViewController(controller1, animated: true)

    }

}

class ProductByCategoryCollectionViewCell: UICollectionViewCell {

    var callProductObject4Cell: Product? {
        didSet {
            productLabel.text = callProductObject4Cell?.name

            // priceLabel.text = String(describing: callProductObject4Cell?.price)

            if let price = callProductObject4Cell?.price {
                priceLabel.text = "$\(price)"
            } else {
                priceLabel.text = ""
            }




            if let profileImageUrl = callProductObject4Cell?.image {
                productImage.loadImageUsingUrlString(profileImageUrl)
            }


        }
    }

    override init(frame: CGRect) {
        super.init(frame: frame)
        setupcategoryCell()
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    let productImage: UIImageView = {
        let image = UIImageView()

        image.image = UIImage(named: "default")
        image.contentMode = .scaleAspectFit
        image.layer.borderWidth = 1
        image.layer.borderColor = UIColor.orange.cgColor
        image.layer.masksToBounds = true
        return image
    }()

    let productLabel: UILabel = {
        let label = UILabel()
        label.text = "productName"
        label.textColor = .black
        label.numberOfLines = 0
        label.font = UIFont.boldSystemFont(ofSize: 10)

        return label
    }()

    let priceLabel: UILabel = {
        let label = UILabel()
        //        label.backgroundColor = .lightGray
        label.text = ""
        label.textColor = .orange
        label.font = UIFont.systemFont(ofSize: 13)

        return label
    }()

    func setupcategoryCell() {

        addSubview(productImage)
        addSubview(productLabel)
        addSubview(priceLabel)

        addConstraintsWithFormat("H:|[v0]|", views: productImage)
        addConstraintsWithFormat("V:|[v0(230)]-2-[v1][v2(10)]-5-|", views: productImage,productLabel, priceLabel)

        addConstraintsWithFormat("H:|[v0]|", views: productLabel)

        addConstraintsWithFormat("H:|[v0]|", views: priceLabel)
    }
}