how to change the position of image inside cell of uitableview

I have added an image to the cell of a uitableview, but when I tried to change the position of the image nothing happened.

This is what my tableview function looks like:

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as UITableViewCell

    let article = articles[indexPath.row] as Article

    cell.textLabel!.text = article.title

    cell.imageView?.image = article.image
    let rect = CGRect(x: 0, y: 0, width: 100, height: 100)
    cell.imageView?.frame = rect

    return cell
}

As you can see the image shows up but the position stays the same:

Any ideas why this happens?