Nested collectionView in a TableView - ios

Question

I've been successfully nesting collections views into tableview for a while now.
What I still don't know how to do, is to do it while respecting the MVC pattern?
Right now I declare my tableview and its cells and in the cell (where the collectionView sits), I attach my collectionView (I got 1 per cell) and do the data mapping. It works, but it's spaghetti code where my View is acting like a controller.
I tried a few times to respect the MVC patterns. I can get my controller to control both my tableview and my collection. Where I struggle is to tell my collection View delegate which data it should pick as all I have as reference is the indexPath (of the collectionView) but not in which tableView that specific collectionView sits.
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionViewCell", for: indexPath) as! CollectionViewCell
return cell
}
The delegate only gives me the indexPath of the cell not which collectionView it is. To use a concrete example - let's assume that my tableview cells represents messages and that each message has a collectionView that controls reactions (like Discord). How do I tell my collectionView delegate which Message it is linked to?
Thanks a lot for the help!

Answer 1

This is very simple. Every view and its subclass has a property tag. You must have an IBOutlet or a simple reference to the CollectionView that sits in the TableViewCell. When you dequeue the TableViewCell just set the tag of your CollectionView equal to the indexPath.row of your tableViewCell like this:
tableViewCell.collectionView.tag = indexPath.row
Then in the UICollectionViewDataSource or UICollectionViewDelegate methods you may find which collectionView it is in other words which tableViewCell does this collectionView sits in. Here's an example:
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionViewCell", for: indexPath) as! CollectionViewCell
let dataObject = dataSourceArray[indexPath.row] as! YourDataModelObject
// Here you may set any property of the collectionView cell
return cell
}
P.S: It is not necessary to respect MVC to that extent. You may manage your CollectionView from the TableViewCell. Have a look at this example.