Swift实现无限轮播效果

import UIKit

classCycleScrollView: UIView, UICollectionViewDelegate,UICollectionViewDataSource {

  var bottomView : UICollectionView?

  var width : CGFloat?

  var height : CGFloat?

  var timer : Timer?

  override init(frame: CGRect){

    super.init(frame: frame)

    // 1.设置背景色

    self.backgroundColor = UIColor.clear

    // 2.设置宽高

    width = self.frame.size.width

    height = self.frame.size.height

    // 3.添加bottomView

    setupBottomView()

    // 4.添加定时器

    setupTimer()

  }

  required init?(coder aDecoder: NSCoder) {

    fatalError("init(coder:) has not been implemented")

  }

  func setupBottomView() {

    // 5.设置collectionView的布局

    let flowLayout = UICollectionViewFlowLayout();

    flowLayout.itemSize = self.bounds.size

    flowLayout.minimumLineSpacing = 0;

    flowLayout.minimumInteritemSpacing = 0;

    flowLayout.scrollDirection = UICollectionViewScrollDirection.horizontal;

    bottomView = UICollectionView.init(frame: self.bounds, collectionViewLayout: flowLayout)

    self.addSubview(bottomView!);

    // 6.设置collectionView的尺寸

    bottomView?.contentSize = CGSize(width:width! * CGFloat(4),height:height!)

    // 7.分页

    bottomView?.isPagingEnabled =true

    // 8.去掉滚动条

    bottomView?.showsVerticalScrollIndicator =false

    bottomView?.showsHorizontalScrollIndicator =false

    // 9.设置代理

    bottomView?.delegate = self

    bottomView?.dataSource = self

    // 10.注册cell

    bottomView?.register(UICollectionViewCell().classForCoder, forCellWithReuseIdentifier:"ID");

    if#available(iOS 10.0, *) {

      // 11.预加载

      bottomView?.isPrefetchingEnabled =true

    }else{

      // Fallback on earlier versions

    }

  }

  func setupTimer() {

    // 12.实例化定时器

    timer = Timer.init(timeInterval: 2, target: self, selector: #selector(timerAction), userInfo: nil, repeats:true);

    RunLoop.main.add(timer!, forMode: RunLoopMode.defaultRunLoopMode);

    DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 2) {

      self.timer?.fire();

    }

  }

  func timerAction() {

    var contentOffsetX = (self.bottomView?.contentOffset.x)! + self.frame.size.width

    ifcontentOffsetX > self.frame.size.width * 3 {

      // 当前视图显示的是第三个的时候，设置bottomView的偏移量为0

      self.bottomView?.contentOffset = CGPoint(x:0,y:0)

      contentOffsetX = self.frame.size.width

    }

     self.bottomView?.setContentOffset(CGPoint(x:contentOffsetX,y:0), animated:true)

  }

  // 重写removeFromSuperview方法，用于删除定时器，否则定时器一直存在，浪费内存

  override func removeFromSuperview() {

    timer?.invalidate()

    timer = nil

    super.removeFromSuperview()

  }

  // Mark:UICollectionViewDataSource

  // 设置Itmes

  func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

    return4;

  }

  // 设置cell

  func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

    let cell : UICollectionViewCell = collectionView.dequeueReusableCell(withReuseIdentifier:"ID",for: indexPath)

    forview : UIView in cell.contentView.subviews {

      view.removeFromSuperview()

    }

    let imageView = UIImageView.init(frame: cell.contentView.bounds)

    ifindexPath.row < 3 {

      imageView.image = UIImage.init(named: String(indexPath.row))

    }else{

      imageView.image = UIImage.init(named: String(0))

    }

    cell.contentView.addSubview(imageView)

    returncell;

  }

  // Mark:UICollectionViewDelegate

  // 点击方法

  func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

    print("您点击了第 (indexPath.row == 3 ? 0 : indexPath.row) 个");

  }

}