ParallaxCollectionViewLayout.02.swift

import UIKit

class ParallaxCollectionViewLayout: UICollectionViewFlowLayout {
    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        return super.layoutAttributesForElements(in: rect)?.flatMap { $0.copy() as? UICollectionViewLayoutAttributes }.flatMap(addParallaxToAttributes)
    }
    
    private func addParallaxToAttributes(_ attributes: UICollectionViewLayoutAttributes) -> UICollectionViewLayoutAttributes {
        return attributes
    }
}