UICollectionViewCells aren't displaying content correctly - ios

Question

I have a two ViewControllers, and each one of them has a collectionView (let's name it CV).
The first CV Cell (named MainPageCell) is the main structure of the app, and among it's other components, it displays an UIView named imageViewGrid.
The purpose of the second controller is only to add it's CV to itself as a subview, and then, it can be added as a child of the first controller and then insert it's view on the imageViewGrid.
In a nutshell, I'm trying to display a CV inside of another CV component. But the cells of the second CV doesn't load, or if they do, they disappear when scrolling. Just one cell can display the content until I scroll.
This GIF describes my situation: Click here
First CV cellForItemAt:
func collectionView(_ collectionView: UICollectionView,
cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: mainReuseIdentifier, for: indexPath) as! MainPageCell
displayController(contentController: photoGridController, on: cell.imageViewGrid)
return cell
}
imageViewGrid declaration inside MainPageCell:
var imageViewGrid: UIView = {
let ivg = UIView()
ivg.backgroundColor = Colors.lightBlue
ivg.translatesAutoresizingMaskIntoConstraints = false
return ivg
}()
DisplayController func:
func displayController(contentController content: UIViewController, on view: UIView) {
addChild(content)
view.addSubview(content.view)
content.view.frame = view.bounds
content.didMove(toParent: self)
}
Second CV cellForItemAt:
func collectionView(_ collectionView: UICollectionView,
cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: photoReuseIdentifier, for: indexPath) as! PhotoGridCell
cell.backgroundColor = Colors.lightBlue
cell.item = names[indexPath.item]
return cell
}
Second CV cell components:
var item: String? {
didSet {
guard let myItem = item,
let image = UIImage(named: myItem) else { return }
if image == UIImage(named: myItem) {
gridImageView.image = image
} else {
gridImageView.image = UIImage(named: "fbicon")
}
}
}
let gridImageView: UIImageView = {
let iv = UIImageView()
iv.contentMode = .scaleAspectFill
iv.translatesAutoresizingMaskIntoConstraints = false
return iv
}()
I don't know if I'm supposed to reload something, or if I forget a step, but couldn't been able to make this work, yet. I'd appreciate some help.