TitledCollectionViewDataSource.swift

    extension TitledCollectionView: UICollectionViewDataSource {
        
        func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
            produce?.count ?? 0
        }

        func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
           
            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: ProduceCollectionViewCell.identifier, for: indexPath) as! ProduceCollectionViewCell
            
            switch produce {
            case .fruit:
                cell.viewModel = Fruit.allCases[indexPath.item].viewModel
            case .vegetable:
                cell.viewModel = Vegetable.allCases[indexPath.item].viewModel
            default: // handles optionality
                break
            }
            
            return cell
            
        }
        
    }