var pageControl:UIPageControl?
  var myscrollView:UIScrollView?
  var myTimer:Timer?
  var mycurrentPage:NSInteger?
  
  
  var courses = [
    ["name":"first","pic":"1.jpeg"],
    ["name":"second","pic":"2.jpeg"],
    ["name":"third","pic":"3.jpeg"]
  ]

 //添加scrollview
    self.addScrollView()
    //添加图片
    self.addImages()
    //添加pagecontrol
    self.addPageControl()
    
    mycurrentPage = 1
    
    //添加定时器
    self.setupTimer()

func addScrollView(){
    self.myscrollView = UIScrollView()
    self.myscrollView?.frame = CGRect(x:0,y:0,width:kScreenWidth,height:kScreenHeight/2)
    self.myscrollView?.contentSize = CGSize(width:kScreenWidth*3,height:kScreenHeight/2)
    self.myscrollView?.showsHorizontalScrollIndicator = false
    self.myscrollView?.showsVerticalScrollIndicator = false
    self.myscrollView?.scrollsToTop = false
    self.myscrollView?.delegate = self
    self.myscrollView?.isPagingEnabled = true
    self.view.addSubview(self.myscrollView!)

  }
  
  func addImages(){
    let size = self.myscrollView?.bounds.size
    for (seq,course) in courses.enumerated() {
      let page = UIView(frame:CGRect(x:0,y:64,width:kScreenWidth,height:kScreenHeight/2))
      let imageView=UIImageView(image:UIImage(named:course["pic"]!))
      imageView.frame = page.frame
      page.addSubview(imageView)
      page.backgroundColor = UIColor.gray
      let lab1 = UILabel(frame:CGRect(x:15,y:kScreenHeight/2-100,width:kScreenWidth-30,height:40))
      lab1.textAlignment = .center
      lab1.backgroundColor = UIColor.red
      lab1.text = course["name"]
      page.addSubview(lab1)
      
      page.frame = CGRect(x:CGFloat(seq)*(size?.width)!,y:0,width:(size?.width)!,height:(size?.height)!)
      self.myscrollView?.addSubview(page)
      
    }
  }
  
  func addPageControl(){
    self.pageControl = UIPageControl(frame:CGRect(x:kScreenWidth/2-50/2,y:kScreenHeight/2-40,width:50,height:35))
    self.pageControl?.backgroundColor = UIColor.blue
    self.pageControl?.numberOfPages = courses.count
    self.view.addSubview(self.pageControl!)
  }
  
  func setupTimer() {
    self.myTimer = Timer.init(timeInterval: 2.0, target: self, selector: #selector(timerAction), userInfo: nil, repeats: true)
    RunLoop.main.add(self.myTimer!, forMode: RunLoopMode.defaultRunLoopMode)
    
//    DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 2) { 
//      self.myTimer?.fire()
//    }
    
  }
  
  func closeTimer(){
    self.myTimer?.invalidate()
    self.myTimer = nil
  }
  
  func timerAction(){
    self.pageControl?.currentPage += mycurrentPage!
    
    if self.pageControl?.currentPage == 0 || self.pageControl?.currentPage == 2 {
      mycurrentPage = -mycurrentPage!
    }
    self.myscrollView?.contentOffset = CGPoint(x:CGFloat(kScreenWidth)*CGFloat((pageControl?.currentPage)!),y:0)
  }

internal func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
    let page = Int(scrollView.contentOffset.x/scrollView.frame.size.width)
    self.pageControl?.currentPage = page
    
  }
  
  func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {
    self.closeTimer()
  }
  
  func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
    self.setupTimer()
  }
  
  func scrollViewWillBeginDecelerating(_ scrollView: UIScrollView) {
    self.pageControl?.currentPage = Int(scrollView.contentOffset.x/kScreenWidth)
  }