dynamically change color of header on selection swift 4 code example

Example: swift how to change the header color

func tableView(tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
    let returnedView = UIView(frame: CGRectMake(x, y, width, height)) //set these values as necessary
    returnedView.backgroundColor = UIColor.lightGrayColor()

    let label = UILabel(frame: CGRectMake(labelX, labelY, labelWidth, labelHeight))
    label.text = self.sectionHeaderTitleArray[section]
    returnedView.addSubview(label)

    return returnedView
}