swift – Fold animation in UICollectionViewLayout in iOS

I need to obtain Fold animation when the person scrolls UICollectionView. I’ve UICollectionView with full-screen dimension cell and vertically scrolling with paging enabled. For that I’ve created sub-class of UICollectionViewFlowLayout which is as described under.

class FoldingFlowLayout: UICollectionViewFlowLayout {
    override func put together() {
        tremendous.put together()
        scrollDirection = .vertical
        minimumLineSpacing = 0
        minimumInteritemSpacing = 0
    }

    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        let attributes = tremendous.layoutAttributesForElements(in: rect)
        attributes?.forEach { attribute in
            transformLayoutAttributes(attribute)
        }
        return attributes
    }

    override func shouldInvalidateLayout(forBoundsChange newBounds: CGRect) -> Bool {
        return true
    }

    non-public func transformLayoutAttributes(_ attributes: UICollectionViewLayoutAttributes) {
        guard let collectionView = collectionView else { return }

        let contentOffsetY = collectionView.contentOffset.y
        let cellOffsetY = attributes.body.origin.y - contentOffsetY
        let cellHeight = attributes.body.peak

        var rework = CATransform3DIdentity
        rework.m34 = -1.0 / 500.0  // Apply perspective

        if cellOffsetY < cellHeight && cellOffsetY > -cellHeight {
            let angle = (cellOffsetY / cellHeight) * .pi / 2
            rework = CATransform3DRotate(rework, angle, -1, 0, 0)
            attributes.transform3D = rework
            attributes.alpha = 1.0 - (abs(cellOffsetY) / cellHeight)
        } else {
            attributes.transform3D = CATransform3DIdentity
            attributes.alpha = 1.0
        }
    }
}

However this isn’t working as I anticipated. I need to create duplicate of this sort of animation.
What am I lacking right here?