Does the UICollectionView display the wrong number of elements when the current cell is not visible?

Question

I have a problem with the elements displayed in mine UICollectionView, which I'm not sure how to explain, but I will be as detailed as possible in the hope that someone can help with this.

I currently have UITableViewCellone that contains UICollectionView. Each UICollectionCellcontains an image extracted from it indexPath.

The following code example is my implementation UITableViewCell, containing UICollectionView:

extension MainViewController: UITableViewDelegate
{
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
    {
        var cell: UITableViewCell = UITableViewCell()

        ....

        if indexPath.section == 4
        {
            if let customCell = tableView.dequeueReusableCell(withIdentifier: "CustomCell", for: indexPath) as? CustomTableViewCell
            {
                if images_ARRAY.isEmpty == false
                {
                    customCell.images_ARRAY = images_ARRAY
                    customCell.awakeFromNib()
                }

                return imagesCell
            }
        }

        return cell
    }
}

class CustomTableViewCell: UITableViewCell
{
    @IBOutlet var imagesCollectionView: UICollectionView!

    var images_ARRAY = [UIImage]()

    var images = [INSPhotoViewable]()

    override func awakeFromNib()
    {
        super.awakeFromNib()
        // Initialization code

        print("awakeFromNib")

        // Through through each image of the record
        for image in images_ARRAY
        {
            images.append(INSPhoto(image: image, thumbnailImage: SomeClass.resized(originalImage: image, withPercentage: 0.3) ) )
        }

        imagesCollectionView.dataSource = self
        imagesCollectionView.delegate = self
    }

    ....

    override func prepareForReuse()
    {
        super.prepareForReuse()

        print("prepareForReuse")

        images.removeAll()
    }
}

extension CustomTableViewCell: UICollectionViewDataSource
{
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int
    {
        return images.count
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell
    {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionViewCell", for: indexPath) as! ExampleCollectionViewCell

        print("indexPath.row = \(indexPath.item)")

        cell.populateWithPhoto(images[indexPath.item])

        return cell
    }
}

I use UIImagePickerControllerin my MainViewControllerway to select an image, set it to UICollectionViewCelland display it in UITableViewCelllike this:

extension MainViewController: UIImagePickerControllerDelegate
{
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any])
    {
        if let selectedImage = info[UIImagePickerControllerOriginalImage] as? UIImage
        {
            // Store and display the image
            if let cell = mainVCTableView.cellForRow(at: IndexPath(row: 0, section: 4) ) as? CustomTableViewCell
            {
                cell.images_ARRAY.append(selectedImage)

                // Remove any existing images before adding all images again
                cell.images.removeAll()

                cell.awakeFromNib()

                cell.imagesCollectionView.reloadData()

                images_ARRAY = cell.images_ARRAY

                if ( (images_ARRAY.count - 1) % 4) == 0 &&
                        images_ARRAY.count != 1
                {
                    self.mainVCTableView.reloadRows(at: [ IndexPath(row: 0, section: 4) ], with: UITableViewRowAnimation.none)
                }
            }
        }

        picker.dismiss(animated: true, completion: nil)
    }

    func imagePickerControllerDidCancel(_ picker: UIImagePickerController)
    {
        picker.dismiss(animated: true, completion: nil)
    }
}

, , images images_ARRAY imagesCollectionView. 4 , UITableViewCell :

5- UITableViewCell , , self.mainVCTableView.reloadRows, , 9, 13, 17 . UITableViewCell:

, 9- , , , self.mainVCTableView.reloadRows, cellForItemAt CustomTableViewCell, indexPath.item 4, 0, 1, 2 ..

The following 2 screenshots when in UICollectionView:

Added image 8th (left) and 9th (right)

As you can see on the right, the 6th, 7th and 8th images have disappeared, and I have an empty row space where the 9th image should be.

Scrolling down the table view shows:

The printout indexPath.itemwhen adding a 9th image shows the following:

indexPath.row = 4
indexPath.row = 0
indexPath.row = 1
indexPath.row = 2
indexPath.row = 3
indexPath.row = 4
indexPath.row = 5
indexPath.row = 6
indexPath.row = 7

However, as soon as I add the 10th image when it reboots imagesCollectionView, all the images reappear again:

The listing after adding the 10th image shows:

indexPath.row = 0
indexPath.row = 1
indexPath.row = 2
indexPath.row = 3
indexPath.row = 4
indexPath.row = 5
indexPath.row = 6
indexPath.row = 7
indexPath.row = 8
indexPath.row = 9

, ? , , - , .

!

Answer 1

@Aravind A R , UICollectionView cellForRowAt :

if images_ARRAY.isEmpty == false
{
    customCell.images_ARRAY = images_ARRAY
    customCell.awakeFromNib()

    customCell.imagesCollectionView.reloadData()
}