var refreshControl = UIRefreshControl()

override func viewDidLoad() {
...
    refreshControl.addTarget(self, action: #selector(TimeLineViewController.refresh), for: UIControlEvents.valueChanged)
    refreshControl.backgroundColor = UIColor.clear
    refreshControl.tintColor = UIColor.darkGray
    refreshControl.clipsToBounds = true

    [UITableViewなど].addSubview(refreshControl)
...
...
}
...
@objc func refresh(){
    //更新時の処理
 }