Transforming a UICollectionViewCell during scrollViewDidScroll with a CGAffineTransform

scrollViewDidScroll.swift

func scrollViewDidScroll(_ scrollView: UIScrollView) {
        if scrollDirection == .horizontal {
            calculateTransforms(with:scrollView.contentOffset)
        }
    }
    
    func calculateTransforms(with offset:CGPoint) {
        guard let collectionView = collectionView else {
            return
        }
        for indexPath in collectionView.indexPathsForVisibleItems {
            if let cell = collectionView.cellForItem(at: indexPath) {
                let halfWidth = cell.contentView.frame.size.width / 2.0
                let realCenter = collectionView.convert(cell.center, to: collectionView.superview)
                let diff = abs(halfWidth - realCenter.x)
                let scale = 1.0 - diff / 1000.0
                let scaleTransform = CGAffineTransform.init(scaleX: scale, y: scale)
                cell.transform = scaleTransform
                cell.alpha = scale
            }
        }
    }