現在基本所有的app都帶有圖片輪滾的廣告頁面或者推薦頁面，圖片輪滾實現的方式有很多種：
最簡單的一種，利用scrollView在前後各加一個輔助的imageView過渡，然後更改scrollView的contentOffset實現圖片輪滾。

第二種，利用三個imageView，add到scrollView上，一直顯示最中間的imageView，每次滾動後，更改scrollView的contentOffset，更新每個imageView的image。

第三種，利用兩個imageView，add到scrollView上，在每次滾動時，判斷滾動方向然後更改沒有顯示的imageView的frame，再更改scrollView的contentOffset，再更新imageView的image.

第四種，利用UICollectionView，每次滾動更改item的順序就可以了。

在這裡實現的第三種方法：

import UIKit

class HGPictureScrollView: UIView, UIScrollViewDelegate {
    var images: Array<UIImage!>!
    var scrollView: UIScrollView!
    var pageControl: UIPageControl!
    var currentImageView: UIImageView!
    var defaultImageView: UIImageView!
    var timer: NSTimer!
    init(frame: CGRect, withImages: Array<UIImage!>) {
        super.init
 
(frame: frame)
        self.images = withImages

        scrollView = UIScrollView.init()
        scrollView.alwaysBounceVertical = false
        scrollView.pagingEnabled = true
        scrollView.showsHorizontalScrollIndicator = false
        scrollView.contentSize = CGSizeMake((self.bounds.size.width
 
 * CGFloat(3)), self.bounds.size.height)
        scrollView.contentOffset.x = self.bounds.size.width
        scrollView.delegate = self
        self.addImages()
        self.addSubview(scrollView)

        pageControl = UIPageControl.init()
        pageControl.numberOfPages = images.count
        pageControl.pageIndicatorTintColor = UIColor.redColor()
        pageControl.currentPageIndicatorTintColor = UIColor.yellowColor()
        self.addSubview(pageControl)

        timer = NSTimer.scheduledTimerWithTimeInterval(1.5, target: self, selector: "next", userInfo: nil, repeats: true)
        //如需在tableView的滾動中也讓timer工作，只需開啟下面的註釋，將上面一句註釋掉
//        timer = NSTimer.init(timeInterval: 1.5, target: self, selector: "next", userInfo: nil, repeats: true)
//        NSRunLoop.currentRunLoop().addTimer(timer, forMode: NSRunLoopCommonModes)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    deinit {
        timer.invalidate()
    }

    //設定兩個imageView的初始image
    func addImages() {
        currentImageView = UIImageView.init(frame: CGRectMake(self.bounds.size.width, 0, self.bounds.size.width, self.bounds.size.height))
        currentImageView.image = images[0]
        scrollView.addSubview(currentImageView)

        defaultImageView = UIImageView.init(frame: CGRectMake(self.bounds.size.width * 2, 0, self.bounds.size.width, self.bounds.size.height))
        defaultImageView.image = images[1]
        scrollView.addSubview(defaultImageView)
    }

    //返回imageView上的image在images中的index
    func indexOfImageView(imageView: UIImageView)->Int {
        return images.indexOf({ (image) -> Bool in
            return (imageView.image?.isEqual(image))!
        })!
    }

    //得到pageControl的currentPage,1.5表示:超過0.5個螢幕大小,就認為發生了page變化
    func currentPageWithImageViews(imageView: UIImageView, rightImageView: UIImageView)->Int {
        return scrollView.contentOffset.x > self.bounds.size.width * 1.5 ? indexOfImageView(rightImageView) : indexOfImageView(imageView)
    }

    //滾動到下一張圖片
    func next() {
        scrollView.scrollRectToVisible(CGRectMake(scrollView.contentOffset.x + self.bounds.size.width, 0, self.bounds.size.width, self.bounds.size.height), animated: true)
    }

    override func layoutSubviews() {
        super.layoutSubviews()

        scrollView.frame = self.bounds

        pageControl.frame = CGRectMake(0, 0, CGFloat(20 * images.count), 20)
        pageControl.center = CGPointMake(self.bounds.width/2, 20)
    }

    func scrollViewDidScroll(scrollView: UIScrollView) {
        //判斷向左還是向右滾動
        if scrollView.contentOffset.x > self.bounds.size.width {
            defaultImageView.frame = CGRectMake(self.bounds.size.width * 2, 0, self.bounds.size.width, self.bounds.size.height)
            //更改副imageView的image
            defaultImageView.image = images[(indexOfImageView(currentImageView) + 1) % images.count]
            //更改pageControl的currentPage
            pageControl.currentPage = currentPageWithImageViews(currentImageView, rightImageView: defaultImageView)
        }
        if scrollView.contentOffset.x < self.bounds.size.width {
            defaultImageView.frame = CGRectMake(0, 0, self.bounds.size.width, self.bounds.size.height)
            defaultImageView.image = images[(indexOfImageView(currentImageView) + images.count - 1) % images.count]
            pageControl.currentPage = currentPageWithImageViews(defaultImageView, rightImageView: currentImageView)
        }
        //這裡是判斷scrollView停止滾動,利用timer讓scrollView滾動時,不走scrollViewDidEndDecelerating方法,無法更換圖片
        if (scrollView.contentOffset.x >= self.bounds.size.width * 2) || (scrollView.contentOffset.x <= 0) {
            scrollView.contentOffset.x = self.bounds.size.width
            currentImageView.image = defaultImageView.image
        }
    }

    func scrollViewWillBeginDragging(scrollView: UIScrollView) {
        timer.fireDate = NSDate.distantFuture()
    }
    func scrollViewDidEndDragging(scrollView: UIScrollView, willDecelerate decelerate: Bool) {
        timer.fireDate = NSDate.init(timeIntervalSinceNow: 1.5)
    }
}