cover flow for horizontal

.swift

  private func updateCellAttributes(by attributes: UICollectionViewLayoutAttributes) {
        var minX = collectionView!.bounds.minX + collectionView!.contentInset.left
        let maxX = attributes.frame.origin.x
        
        if minX > attributes.frame.origin.x + attributes.bounds.width + minimumLineSpacing + collectionView!.contentInset.left {
            minX = 0
        }
        let finalX = max(minX, maxX)
        var origin = attributes.frame.origin
        let deltaX = (finalX - origin.x) / attributes.frame.width
        let translationScale = CGFloat((attributes.zIndex + 1) * 10)
        
        // Card stack effect
        if let itemTransform = firstItemTransform {
            let scale = 1 - deltaX * itemTransform
            
            var t = CGAffineTransform.identity
            
            t = t.scaledBy(x: scale, y: scale)
            if isPreviousCardVisible {
                t = t.translatedBy(x: (deltaX * translationScale), y: 0)
            }
            
            attributes.transform = t
            attributes.alpha = scale
        }
        
        origin.x = finalX
        
        origin.y = collectionView!.frame.height / 2 - attributes.frame.height / 2 - collectionView!.contentInset.top
       
        attributes.frame = CGRect(origin: origin, size: attributes.frame.size)
        attributes.zIndex = attributes.indexPath.row
    }