Argthtjtr

I am working on an application where I get 100 data from my backend API, I am displaying this data in a collectionView but displaying 100 data at once could be very long and annoying so I want to implement pagination to the UICollectionView, through my research, I tried implementing some of the code line I got but when ever I scroll up, I see nothing. No UIActivityIndicator shows nothing. I have searched for this for about three straight days but nothing positive. I have pasted my code below with hopes of someone helping with it. Thanks in advance

class MainVC: UIViewController {



    @IBOutlet weak var collectionView: UICollectionView!

    @IBAction func prepareForUnwind(segue: UIStoryboardSegue) {}

    @IBOutlet weak var spinner: UIActivityIndicatorView!



    var itemArray = OfflineFunctions.instance.getDataFromDB()

    var flickrArray = ServiceProvider.instance.flickerPhotos // This returns 100 items



    var offline: Bool = false

    var isLoadMore: Bool = false

    var isLastPageReached: Bool = false

    var limit = 10

    let totalEntries = ServiceProvider.instance.flickerPhotos.count // This returns 100 items



    override func viewDidLoad() {

        super.viewDidLoad()



        collectionView.delegate = self

        collectionView.dataSource = self

        setupWithPhotos()

        collectionView.isPagingEnabled = true



    }





    override func viewDidAppear(_ animated: Bool) {

        super.viewDidAppear(animated)

        collectionView.reloadData()

    }



    // Function that gets the items 



    func setupWithPhotos() -> Void {



        spinner.isHidden = false

        spinner.startAnimating()



        ServiceProvider.instance.getPhotos {[weak self] (success, error) in

            if success {

                self?.collectionView.reloadData()

                self?.spinner.isHidden = true

                self?.spinner.stopAnimating()



                self?.offline = false

            }



            if error != nil {



                alert.addAction(UIAlertAction(title: "Ok", style: .cancel) { (action:UIAlertAction!) in

                    self?.spinner.isHidden = true

                    self?.spinner.stopAnimating()

                    self?.collectionView.reloadData()

                    self?.offline = true

                })



                self?.present(alert, animated: true)

            }

        }

    }



    @IBAction func reloadPressed(_ sender: Any) {

        setupWithPhotos()

    }



    @IBAction func closePressed(_ sender: Any) {

        performSegue(withIdentifier: UNWIND, sender: nil)

    }



    func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {

        targetContentOffset.pointee = scrollView.contentOffset

        var indexes = self.collectionView.indexPathsForVisibleItems

        indexes.sort()

        var index = indexes.first!

        let cell = self.collectionView.cellForItem(at: index)!

        let position = self.collectionView.contentOffset.y - cell.frame.origin.y

        if position > cell.frame.size.height/2{

            index.row = index.row+1

        }

        self.collectionView.scrollToItem(at: index, at: .left, animated: true )

    }



}



extension MainVC: UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {



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





        if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: PHOTO_CELL, for: indexPath) as? MainCell {



            cell.offline = offline

            if !offline {



                 let flickerPhoto = ServiceProvider.instance.flickerPhotos[indexPath.row]

                cell.configueCell(flickerPhotoModel: flickerPhoto, index: indexPath.item)

                return cell

            } else {



                let flickerPhoto = itemArray[indexPath.row]

                cell.configueOfflineCell(flickerPhotoModel: flickerPhoto, index: indexPath.item)

                return cell

            }

        }

        return MainCell()

    }



    func numberOfSections(in collectionView: UICollectionView) -> Int {

        return 1

    }



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

        if !offline {

            return ServiceProvider.instance.flickerPhotos.count

        } else {

            return itemArray.count

        }



    }



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

        // setting cells based on screen size



        var numOfColums : CGFloat = 2

        if UIScreen.main.bounds.width > 320 {

            numOfColums = 1

        }



        let spaceBtwCells : CGFloat = 10

        let padding: CGFloat = 40

        let cellDimension = ((collectionView.bounds.width - padding) - (numOfColums - 1) * spaceBtwCells) / numOfColums



        return CGSize(width: cellDimension, height: cellDimension)



    }







    func collectionView(_ collectionView: UICollectionView, layout

        collectionViewLayout: UICollectionViewLayout,

                        referenceSizeForFooterInSection section: Int) -> CGSize {



        if flickrArray.count > 0 && isLastPageReached == false {

            return CGSize(width:(collectionView.frame.size.width), height: 100.0)

        }

        return CGSize.zero



    }



    func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {



        if kind == UICollectionView.elementKindSectionFooter {



            let vew = collectionView.dequeueReusableSupplementaryView(ofKind: UICollectionView.elementKindSectionFooter, withReuseIdentifier: "footer", for: indexPath)





            let loading = UIActivityIndicatorView()

            loading.style = .gray

            loading.translatesAutoresizingMaskIntoConstraints = false

            loading.tintColor = UIColor.gray

            loading.tag = -123456

            vew.addSubview(loading)

            vew.addConstraint(NSLayoutConstraint(item: loading, attribute: .centerX, relatedBy: .equal, toItem: vew, attribute: .centerX, multiplier: 1, constant: 0))

            vew.addConstraint(NSLayoutConstraint(item: loading, attribute: .centerY, relatedBy: .equal, toItem: vew, attribute: .centerY, multiplier: 1, constant: 0))





            return vew

        }

        return UICollectionReusableView()

    }



    func collectionView(_ collectionView: UICollectionView, willDisplaySupplementaryView view: UICollectionReusableView, forElementKind elementKind: String, at indexPath: IndexPath) {

        if elementKind == UICollectionView.elementKindSectionFooter {



            if let loadingView = view.viewWithTag(-123456) as? UIActivityIndicatorView{

                if flickrArray.count > 0 && isLastPageReached == false {

                    loadingView.startAnimating()

                    print("END REACH 1")

                }

                else {

                    self.isLoadMore = false

                }

            }

        }

    }



    func collectionView(_ collectionView: UICollectionView, didEndDisplayingSupplementaryView view: UICollectionReusableView, forElementOfKind elementKind: String, at indexPath: IndexPath) {

        if elementKind == UICollectionView.elementKindSectionFooter{



            if let loadingView = view.viewWithTag(-123456) as? UIActivityIndicatorView{

                loadingView.stopAnimating()

                loadingView.removeFromSuperview()



                self.isLoadMore = false

            }



        }

    }



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





        if !offline {

            let flickerPhoto = ServiceProvider.instance.flickerPhotos[indexPath.item]

            ServiceProvider.instance.selectedPhoto = flickerPhoto

            performSegue(withIdentifier: DETAIL_VC_SEGUE, sender:indexPath)

        } else {

            let offlineList = OfflineFunctions.instance.offlineItems?[indexPath.item]

            OfflineFunctions.instance.selectedImage = offlineList

            performSegue(withIdentifier: MAIN_TO_SAVED_DETAIL_VC_SEGUE, sender:indexPath)

        }

        NotificationCenter.default.post(name: NOTIFY_PHOTO_SELECTED, object: nil)





    }



    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

        if (segue.identifier == SAVED_DETAIL_VC) {



            let popUp = segue.destination as! SavedDetailVC

            popUp.doneSaving = { [weak self] in

                self?.collectionView.reloadData()

            }



        }

    }



}

here is a link to my API get https://www.flickr.com/services/api/explore/flickr.photos.getRecent
further codes would be added on request