Cached shadow path for UITableView

I want to cache a shadow path to make the performance of UITableView better.

I've read https://yalantis.com/blog/mastering-uikit-performance/ that

if let rect = cell.imageView?.bounds {
    cell.imageView?.layer.shadowPath = UIBezierPath(rect: rect).cgPath
}

would stop offscreen shadows, however using the following function

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
        cell.textLabel?.text = "Cell data: \(data[indexPath.row])"
        
        if let rect = cell.imageView?.bounds {
          cell.imageView?.layer.shadowPath = UIBezierPath(rect: rect).cgPath
        }
        
        cell.imageView?.layer.shadowRadius = 8
        cell.imageView?.layer.shadowOffset = CGSize(width: 3, height: 3)
        cell.imageView?.layer.shadowOpacity = 0.5
        
        
        cell.imageView?.layer.cornerRadius = 20
        cell.imageView?.image = UIImage(named: "PlaceholderImage")
        return cell
    }

produces a result where some cells have the shadow and some don't.

How can I implement caching of shadow paths to all cells in a simple UITableView