向滚动后删除的UITableViewCell添加CALayer

I am trying to add a CALayer to the bottom part of my UITableViewCell to get a bit of a "shadow" effect. The problem is when the table is scrolled up and off the screen the layer is removed, so when you scroll back down it isn't visible. If you scroll the cells downward off the screen then back up they appear fine. I am trying to add a CALayer to the bottom part