Swift tableview自带的刷新控件

import UIKit

class ViewController: UIViewController,UITableViewDelegate,UITableViewDataSource {

    let tableview = UITableView(frame: ScreenRect, style: .plain)
    let refreshControl = UIRefreshControl()
    let cell = "cell"
    var arraymutable = ["","","","",""]
    let array = ["","","",""]

    override func viewDidLoad() {
        super.viewDidLoad()
self.view.backgroundColor = #colorLiteral(red: , green: , blue: , alpha: )
        CreatUi()

        // Do any additional setup after loading the view.
    }

    func CreatUi(){

        tableview.separatorStyle = .singleLine
        tableview.backgroundColor = #colorLiteral(red: , green: , blue: , alpha: )
        tableview.delegate = self
        tableview.dataSource = self
        tableview.tableFooterView = UIView()
        tableview.refreshControl = refreshControl

        refreshControl.backgroundColor = UIColor.gray
        refreshControl.attributedTitle = NSAttributedString(string: "刷新一下：\(NSDate())", attributes: [NSForegroundColorAttributeName:UIColor.white])//设置文字颜色
        refreshControl.tintColor = UIColor.green //小菊花的颜色
        refreshControl.tintAdjustmentMode = .dimmed //色彩调整模式

        refreshControl.addTarget(self, action: #selector(addcount), for: .valueChanged)

        view.addSubview(tableview)

    }

    func addcount(){

        arraymutable.append(contentsOf: array)
        tableview.reloadData()
        refreshControl.endRefreshing()

    }
    override var preferredStatusBarStyle: UIStatusBarStyle{

        return .default
    }

    //tableview 代理
    func numberOfSections(in tableView: UITableView) -> Int {
        return
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return arraymutable.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        let celll = tableView.dequeueReusableCell(withIdentifier: cell) ?? UITableViewCell(style: .default, reuseIdentifier:cell)

        celll.textLabel?.text = arraymutable[indexPath.row]
        celll.textLabel?.textColor = UIColor.red
        celll.textLabel?.font = UIFont.boldSystemFont(ofSize: )

        return celll

    }

    func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
        return
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

}