UIPageControl 和 UIScrollView 不滚动

Question

我有一个相对简单的UIViewController，其中UIScrollView 占据了屏幕的一半，UIImageView 放置在UIScrollView 内，与UIScrollView 的大小完全相同。

在UIImageView 之上还有一个UIPageControl。重点是具有水平滚动并根据数组中图像的数量呈现像滑块一样的图像。问题是滚动视图没有滚动，我不知道为什么。

 @IBOutlet weak var scrollView: UIScrollView!
@IBOutlet weak var imageView: UIImageView!
@IBOutlet weak var pageControl: UIPageControl!

let imagelist = ["3.jpg", "1.jpg", "2.png", "4.png", "5.png"]

override func viewDidLoad() {
    super.viewDidLoad()
    scrollView.delegate = self
    configurePageControl()

    for  i in stride(from: 0, to: imagelist.count, by: 1) {
        var frame = CGRect.zero
        frame.origin.x = self.scrollView.frame.size.width * CGFloat(i)
        frame.origin.y = 0
        frame.size = self.scrollView.frame.size
        scrollView.isPagingEnabled = true
        scrollView.isScrollEnabled = true

        let myImage:UIImage = UIImage(named: imagelist[i])!
        let bgColorFromImage = myImage.averageColor
        imageView.image = myImage
        imageView.contentMode = UIViewContentMode.scaleAspectFit
        imageView.frame = frame


        scrollView.backgroundColor = bgColorFromImage
        scrollView.addSubview(imageView)
    }

    self.scrollView.contentSize = CGSize(width: self.scrollView.frame.size.width * CGFloat(imagelist.count), height: self.scrollView.frame.size.height)
    pageControl.addTarget(self, action: #selector(changePage), for: UIControlEvents.valueChanged)

}

func configurePageControl() {
    self.pageControl.numberOfPages = imagelist.count
    self.pageControl.currentPage = 0
    self.pageControl.tintColor = UIColor.red
    self.pageControl.pageIndicatorTintColor = UIColor.black
    self.pageControl.currentPageIndicatorTintColor = UIColor.green
    self.imageView.addSubview(pageControl)
}

@objc func changePage() {
    let x = CGFloat(pageControl.currentPage) * scrollView.frame.size.width
    scrollView.setContentOffset(CGPoint(x: x,y :0), animated: true)
}

func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
    let pageNumber = round(scrollView.contentOffset.x / scrollView.frame.size.width)
    pageControl.currentPage = Int(pageNumber)
}

这就是UIStoryboard 的样子：

Answer 1

在 for 循环中你使用 imageView 的同一个对象，你只设置框架和图像

imageView.frame = frame
imageView.image = myImage

但您必须创建UIImageView 的新实例

//

假设您在 IB 中有一个 scrollView ，它对 superView 具有 top 、前导和尾随约束，并且高度为 200 ，您可以像这样动态添加 imageViews

class ViewController: UIViewController {

    @IBOutlet weak var scrollView: UIScrollView!

    override func viewDidLoad() {
        super.viewDidLoad()


        for i in 0..<10 {

            let f = CGRect(x: CGFloat(i) * scrollView.frame.width, y: 0, width: scrollView.frame.width, height: scrollView.frame.height)

            let imgV = UIImageView(frame: f)

            imgV.image = UIImage(named: "re-fuel.png")

            scrollView.addSubview(imgV)


        }

        scrollView.contentSize = CGSize(width: CGFloat(10) * scrollView.frame.width, height: scrollView.frame.height)
    }
}

结果

Answer 2

问题在于滚动视图本身是使用自动布局定位的。一旦你这样做了，你就不能设置contentSize 来使滚动视图可滚动。您必须使用内部约束来配置内容大小。