//Define what card should we drag
    fileprivate func findDraggingCellByCoordinate(_ touchCoordinate: CGPoint) {
        if let indexPath = collectionView?.indexPathForItem(at: touchCoordinate) {
            if indexPath.item >= index {
                //top stack
                draggedCellPath = IndexPath(item: index, section: 0)
                initialCellCenter = collectionView?.cellForItem(at: draggedCellPath!)?.center
            } else {
                //bottomStack
                if (index > 0 ) {
                    draggedCellPath = IndexPath(item: index - 1, section: 0)
                }
                initialCellCenter = collectionView?.cellForItem(at: draggedCellPath!)?.center
            }
            
            //workaround for fix issue with zIndex
            let cell = collectionView!.cellForItem(at: draggedCellPath!)
            collectionView?.bringSubview(toFront: cell!)
            
        }
    }