An example of what you could find in a UICollectionViewDataSource

WUCFCollectionViewDataSource.swift

class StandardCell: UICollectionViewCell {
    
    var titleLabel: UILabel!
}

class StandardDataSource: NSObject, UICollectionViewDataSource {
    
    var firstSectionItems: [String] = ["first", "second", "third"]
    var secondSectionItems: [String] = ["FIRST", "SECOND", "THIRD"]

    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 2
    }

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        if section == 0 {
            return firstSectionItems.count
            
        } else if section == 1 {
            return secondSectionItems.count
        } else {
            return 0
        }
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath)
        guard let standardCell = cell as? StandardCell else {
            return cell
        }
        
        if indexPath.section == 0 {
            
            standardCell.titleLabel.text = self.firstSectionItems[indexPath.item]
            
        } else if indexPath.section == 1 {

            standardCell.titleLabel.text = self.firstSectionItems[indexPath.item]
        }
        
        return cell
    }
}