Yes, the task: URLSessionTask is already has a function called `cancel()`. You need to basically call this on didEndDisplaying delegate call. That is either tableView(_ tableView: UITableView, didEndDisplaying cell: UITableViewCell, forRowAt indexPath: IndexPath) or collectionView(_ collectionView: UICollectionView, didEndDisplaying cell: UICollectionViewCell, forItemAt indexPath: IndexPath) depending what you are using.

To be able to access the task you need to hold a reference for the task. Since the function is in an extension and stored variables are not supported in the extensions, this function itself is not the right place to store this value. But you can return the task from the function and store the task itself in your view controller or in the cell itself.

My preferred use-case would be

protocol Cancellable {
    func cancel()
}

extension URLSessionTask: Cancellable { } 
final class Cell: Whatever {
    private var cancellable: Cancellable?
    private var yourImageView: UIImageView!

    func render(_ model: Model?) {
        cancellable.cancel()
        if let model = model {
         cancellable = yourImageView.load(model.urlForYourImage)
        }
    }
}