ScrollView Doesn't Scroll in collectionViewCell - ios

Question

I am creating a collage app. The functionality I am looking at in my collectionViewCell is exactly like this: How to make a UIImage Scrollable inside a UIScrollView?
What I have done till now:
Created a custom collectionViewCell embedded a UIScrollView in it and an imageView inside the scrollView. I have set their constraints. Following is my code for collectionViewCell :
override init(frame: CGRect) {
super.init(frame: frame)
// addSubview(scrollView)
insertSubview(scrollView, at: 0)
contentView.isUserInteractionEnabled = true
scrollView.contentMode = .scaleAspectFill
scrollView.translatesAutoresizingMaskIntoConstraints = false
scrollView.addSubview(imageView)
scrollContentView.translatesAutoresizingMaskIntoConstraints = false
scrollView.isScrollEnabled = true
imageView.isUserInteractionEnabled = false
scrollView.delegate = self
scrollView.maximumZoomScale = 5.0
scrollView.backgroundColor = .red
scrollViewDidScroll(scrollView)
// scrollViewWillBeginDragging(scrollView)
let constraints = [
// Scroll View Constraints
scrollView.topAnchor.constraint(equalTo: contentView.topAnchor,constant: 0.0)
scrollView.bottomAnchor.constraint(equalTo: contentView.bottomAnchor,constant: 0.0),
scrollView.trailingAnchor.constraint(equalTo: contentView.trailingAnchor,constant: 0.0),
scrollView.leadingAnchor.constraint(equalTo: contentView.leadingAnchor,constant: 0.0),
// ImageView Constraints
imageView.topAnchor.constraint(equalTo: self.scrollView.topAnchor),
imageView.bottomAnchor.constraint(equalTo: self.scrollView.bottomAnchor),
imageView.trailingAnchor.constraint(equalTo: self.scrollView.trailingAnchor),
imageView.leadingAnchor.constraint(equalTo: self.scrollView.leadingAnchor)
]
NSLayoutConstraint.activate(constraints)
}
Another issue I face here is if I do insertSubview() instead of addSubview my collectionView function for didselectItemAt works fine else if I use addSubView the didselectItemFunction doesn't execute. Code For didSelectItem :
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
if selectedImage[indexPath.row] != UIImage(named: "empty-image") {
collectionViewCellClass.scrollView.isUserInteractionEnabled = true
collectionViewCellClass.scrollViewDidScroll(collectionViewCellClass.scrollView)
collectionViewCellClass.scrollView.showsHorizontalScrollIndicator = true
}else {
collectionViewCellClass.imageView.isUserInteractionEnabled = false
self.currentIndex = indexPath.row
if UIImagePickerController.isSourceTypeAvailable(.photoLibrary){
imagePicker.delegate = self
imagePicker.allowsEditing = false
imagePicker.sourceType = .savedPhotosAlbum
present(imagePicker, animated: true, completion: nil)
}
}
}
Code for CellForItemAt IndexPath :
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! CollectionViewCell
cell.imageView.image = selectedImage[indexPath.item]
// TODO: Round corners of the cell
cell.scrollView.frame = CGRect(x: 0, y: 0, width: cell.frame.size.width, height: cell.frame.size.height)
// cell.scrollView.contentSize = CGSize(width: cell.imageView.image!.size.width * 2, height: cell.imageView.image!.size.height * 2)
cell.scrollView.contentSize = cell.imageView.image?.size ?? .zero
cell.scrollView.contentMode = .center
cell.scrollView.isScrollEnabled = true
// cell.scrollContentView.frame = CGRect(x: 0, y: 0, width: cell.frame.size.width, height: cell.frame.size.height)
cell.imageView.frame = CGRect(x: 0, y: 0, width: cell.imageView.image!.size.width, height: cell.imageView.image!.size.height)
// cell.imageView.clipsToBounds = true
cell.backgroundColor = .black
return cell
}
I have tried changing the size of ImageView = cell.frame.size still no luck and changed the size for scrollView Frame as well to imageView.image.size but for some reason scrollView doesn't scroll.

Answer 1

Insertview vs addSubview
addSubview: add the view at the frontmost.
insertSubview: add the view at a specific index.
when you add your scrollview it using addSubView method it will block all the user interaction for the view's that are below it. That's why didSelect event is not triggered.
see this question
To make the scrollview scroll you need to set its contentSize which should be greater than scrollview's frame. try adding an image whose size is greater than collectionview cell.
scrollView.contentSize = imageView.bounds.size

Answer 2

Try adding the scrollView to the cells contentView:
self.contentView.addSubview(scrollView)

Answer 3

I finally found the Solution, following is what worked for me :
if selectedImage[indexPath.row] != UIImage(named: "empty-image"){
cell.contentView.isUserInteractionEnabled = true
}else{
cell.contentView.isUserInteractionEnabled = false
}
The UIImage(named: "empty-image") is the image that appears when a user doesn't have made any selection for his image. I wrote the above code in the cellForItemAt function. Also, I had to set imageView.frame equal to the original width and height of the image.
cell.imageView.frame = CGRect(x: 0, y: 0, width: cell.imageView.image!.size.width, height: cell.imageView.image!.size.height)
The above solution solved my problem. Hopefully, it will help someone.