Reuse item inside a row when scrolling - ios

Question

I have collectionView inside tableView. collectionView need to horizontal scroll image, tableView for vertical scroll posts. When I had 3 rows I had no problems, but when i create 4 rows i have a problem with scrolling items inside rows. If I start scrolling on 4 row, scrolling is repeated on row 1 and the same thing if i start scrolling on 1 row scrolling is repeating on row 4.
What could be the problem and how to solve it? May be
Can check .gif file. I start on 1 row on name "Oko" and if i scrolling down on 4 row and scroll right collectionCell and return on 1 row i see next image name "City", but there must be name "Oko"
My code:
ViewController:
class PhotoStudiosViewController: UIViewController, UITableViewDelegate, UITableViewDataSource, UISearchResultsUpdating {
#IBOutlet weak var tableView: UITableView!
var theStudios: [Studio] = []
var filteredStudios: [Studio] = []
var studiosRef: DatabaseReference!
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(true)
tableView.estimatedRowHeight = 475
tableView.rowHeight = UITableViewAutomaticDimension
}
override func viewDidLoad() {
super.viewDidLoad()
studiosRef = Database.database().reference(withPath: "PhotoStudios1")
studiosRef.observe(.value, with: { (snapshot) in
for imageSnap in snapshot.children {
let studioObj = Studio(snapshot: imageSnap as! DataSnapshot)
self.theStudios.append(studioObj)
}
self.tableView.reloadData()
})
}
// MARK: - TableView
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if searchController.isActive && searchController.searchBar.text != "" {
return filteredStudios.count
}
return theStudios.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "tableCell", for: indexPath) as! PhotoStudiosTableViewCell
cell.currentPageNumber.text = "1/\(theStudios[indexPath.row].halls.count)"
if searchController.isActive && searchController.searchBar.text != nil {
cell.theHalls = filteredStudios[indexPath.row].halls
} else {
cell.theHalls = theStudios[indexPath.row].halls
}
cell.nameLabel.text = theStudios[indexPath.row].studioName
cell.addressLabel.text = theStudios[indexPath.row].studioAddress
cell.logoLabel.sd_setImage(with: URL(string: theStudios[indexPath.row].studioLogo))
cell.didSelectAction = {
(innerPath) in
self.showDetailsView(indexPath, cellPath: innerPath)
}
return cell
}
TableViewCell:
class PhotoStudiosTableViewCell: UITableViewCell, UICollectionViewDelegate, UICollectionViewDataSource, UIScrollViewDelegate, UICollectionViewDelegateFlowLayout {
#IBOutlet weak var button: UIButton!
#IBOutlet weak var logoLabel: UIImageView!
#IBOutlet weak var nameLabel: UILabel!
#IBOutlet weak var addressLabel: UILabel!
#IBOutlet weak var collectionView: UICollectionView!
#IBOutlet weak var currentPageNumber: UILabel!
var didSelectAction: ((IndexPath) -> ())?
var theHalls: [Hall] = [] {
didSet {
collectionView.reloadData()
}
}
var lastContentOffset = CGPoint.zero
override func prepareForReuse() {
super.prepareForReuse()
resetCollectionView()
}
override func awakeFromNib() {
super.awakeFromNib()
currentPageNumber.layer.zPosition = 2
currentPageNumber.layer.cornerRadius = 15.0
currentPageNumber.clipsToBounds = true
}
func resetCollectionView() {
guard !theHalls.isEmpty else { return }
theHalls = []
collectionView.reloadData()
}
// MARK: - CollectionView
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return theHalls.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "collectionCell", for: indexPath) as! PhotoStudiosCollectionViewCell2
cell.hallName.text = theHalls[indexPath.item].hallName
cell.priceLabel.text = theHalls[indexPath.item].hallPrice
cell.metrslabel.text = theHalls[indexPath.item].hallMetrs
cell.photoStudioImage.sd_setImage(with: URL(string: theHalls[indexPath.item].hallImage))
return cell
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
didSelectAction?(indexPath)
}
}

Answer 1

You're reusing the collection views in your cells, which is correct, but that means the contentOffset is also left from whatever was scrolled to previously when a cell is reused. It should be sufficient to just reset the contentOffset in cellForRowAtIndexPath when you are setting up your cell by doing something like:
cell.collectionView.contentOffset = .zero
One thing worth mentioning is that I do see you have a property called lastContentOffset in your cells that doesn't do anything yet and I suspect you are going to try to use that to persist the offset for a given cell when it scrolls out of view so that you can set it again when it comes back into view (rather than always resetting).
If you are going to do that, having the property in the cell won't work. You'll need to have a list of offsets for each cell stored alongside your data models in the containing view controller. Then you might save the offset for a given cell in didEndDisplayingCell and setting it in cellForRowAtIndexPath instead of .zero as I did above.