Image not round

I've tried your code and tested the value of cell.imageView?.frame.size.height

At this point in code, it is not yet set, hence a value of 1.

If you replace by a fix value that you compute, like

cell.imageView?.layer.cornerRadius = 30 // (cell.imageView?.frame.size.height)!/2

You should see some effect

Here is the complete part of code, in tableView(cellForRowAt)

                   let itemSize = CGSize.init(width: 80, height: 80) 
                   let imageRect : CGRect = CGRect(x: 0, y: 0, width: 80, height: 80)
                   UIGraphicsBeginImageContextWithOptions(itemSize, true, UIScreen.main.scale);
                    cell.imageView?.layer.borderWidth=1.0
                    cell.imageView?.layer.masksToBounds = true
                    cell.imageView?.layer.borderColor = UIColor.white.cgColor
                    cell.imageView?.layer.cornerRadius = 40
                    cell.imageView?.clipsToBounds = true
                    cell.imageView?.image!.draw(in: imageRect)
                    cell.imageView?.image! = UIGraphicsGetImageFromCurrentImageContext()!;
                    UIGraphicsEndImageContext()

Thank you but it crashes on this line:

        cell.imageView?.image!.draw(in: imageRect)

oh yes. I copied from other code.

you have to set image view?.image before With

cell.imageView!.image = UIImage(data: data)