bottom border for collection view

Picture a 3x3 grid, there is a high chance that the bottom row of the grid is 50% thinner than the other borders in the collectionview since there is only 1 border there(instead of 2)

            let border = CALayer()

            //width of border

            let width = CGFloat(1.0)

            //border color

            border.borderColor = UIColor(red: 216.0/255.0, green: 216.0/255.0, blue: 216.0/255.0, alpha: 1.0).CGColor

            border.frame = CGRect(x: 0, y: cell.frame.size.height - width, width:  cell.frame.size.width, height: cell.frame.size.height)

            border.borderWidth = width

            cell.layer.addSublayer(border)

            cell.layer.masksToBounds = true