How do I create a custom view in a custom table view cell?

I am trying to create a custom checkbox inside of a custom table view cell.

I have a custom table view cell:

class CustomTableViewCell: UITableViewCell {
   weak var delegate: CellDelegateT?
   @IBOutlet var customCheckbox: VKCheckbox!
}

Here's the code to load my tableView:

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! TransactionsTableViewCell
    let customCheckbox = cell.customCheckbox!
    customCheckbox.line = .thin
    customCheckbox.bgColor = UIColor.white
    customCheckbox.color = UIColor.black
    customCheckbox.borderColor = UIColor.black
    customCheckbox.borderWidth = 2
    customCheckbox.cornerRadius = customCheckbox.frame.height / 2
}

Where do I need to place the code that constructs the checkbox? Is the cellForRowAt not the correct place?

When I use the code outside of my table cell, it works fine. That's why I think I am placing the checkbox creation code in the wrong place.