嘿，我刚好折腾过这种无限滚动背景效果，给你分享两种靠谱的实现思路，都能达到你要的那种连续无缝的滚动效果：

方法一：用CALayer做自动滚动背景 #

这种方法适合不需要用户交互、纯自动滚动的场景，核心思路是把两张完全相同的图片层叠在一起，通过动画让它们持续平移，当第一张图片完全移出屏幕时，瞬间重置位置，视觉上就像无限循环了。

代码示例： #

import UIKit

class InfiniteBackgroundView: UIView {
    private let scrollLayer = CALayer()
    private let imageLayer1 = CALayer()
    private let imageLayer2 = CALayer()
    private var scrollAnimation: CABasicAnimation?
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        setupLayers()
        startScrolling()
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        setupLayers()
        startScrolling()
    }
    
    private func setupLayers() {
        guard let image = UIImage(named: "your-background-image") else { return }
        
        // 配置两个图片层，第二张放在第一张的右侧
        imageLayer1.contents = image.cgImage
        imageLayer1.frame = bounds
        imageLayer2.contents = image.cgImage
        imageLayer2.frame = CGRect(x: bounds.width, y: 0, width: bounds.width, height: bounds.height)
        
        scrollLayer.addSublayer(imageLayer1)
        scrollLayer.addSublayer(imageLayer2)
        scrollLayer.frame = bounds
        layer.addSublayer(scrollLayer)
    }
    
    private func startScrolling() {
        // 创建平移动画，让整个scrollLayer向左移动一个屏幕宽度
        scrollAnimation = CABasicAnimation(keyPath: "transform.translation.x")
        scrollAnimation?.fromValue = 0
        scrollAnimation?.toValue = -bounds.width
        scrollAnimation?.duration = 10 // 滚动速度，数值越小越快
        scrollAnimation?.repeatCount = .infinity
        scrollAnimation?.isRemovedOnCompletion = false
        scrollAnimation?.fillMode = .forwards
        
        scrollLayer.add(scrollAnimation!, forKey: "infiniteScroll")
    }
    
    // 暂停/继续滚动的方法（可选）
    func toggleScrolling() {
        let paused = scrollLayer.speed == 0
        scrollLayer.speed = paused ? 1 : 0
    }
}

注意：把"your-background-image"换成你实际的图片名称，调整duration可以控制滚动速度

方法二：用UIScrollView实现可交互的无限滚动 #

如果需要支持用户手动滑动，同时保持无限循环的效果，这种方法更合适。原理是在scrollView里放置三张相同的图片（左、中、右），当用户滚动到最左边或最右边时，立刻将scrollView的contentOffset重置到中间位置，视觉上就像没有边界一样。

代码示例： #

import UIKit

class InfiniteScrollViewController: UIViewController, UIScrollViewDelegate {
    private let scrollView = UIScrollView()
    private let imageView1 = UIImageView()
    private let imageView2 = UIImageView()
    private let imageView3 = UIImageView()
    private let imageName = "your-background-image"
    
    override func viewDidLoad() {
        super.viewDidLoad()
        setupScrollView()
        setupImageViews()
        startAutoScroll() // 如果需要自动滚动的话，不需要可以删掉
    }
    
    private func setupScrollView() {
        scrollView.delegate = self
        scrollView.frame = view.bounds
        scrollView.isPagingEnabled = true
        scrollView.showsHorizontalScrollIndicator = false
        scrollView.contentSize = CGSize(width: view.bounds.width * 3, height: view.bounds.height)
        view.addSubview(scrollView)
        
        // 初始位置设置在中间的图片
        scrollView.setContentOffset(CGPoint(x: view.bounds.width, y: 0), animated: false)
    }
    
    private func setupImageViews() {
        guard let image = UIImage(named: imageName) else { return }
        
        let imageViews = [imageView1, imageView2, imageView3]
        for (index, iv) in imageViews.enumerated() {
            iv.image = image
            iv.frame = CGRect(x: CGFloat(index) * view.bounds.width, y: 0, width: view.bounds.width, height: view.bounds.height)
            scrollView.addSubview(iv)
        }
    }
    
    func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
        resetScrollPosition()
    }
    
    func scrollViewDidEndScrollingAnimation(_ scrollView: UIScrollView) {
        resetScrollPosition()
    }
    
    private func resetScrollPosition() {
        let currentOffsetX = scrollView.contentOffset.x
        // 滚动到最左边（第一张图），立刻跳回中间（第二张图）
        if currentOffsetX == 0 {
            scrollView.setContentOffset(CGPoint(x: view.bounds.width, y: 0), animated: false)
        }
        // 滚动到最右边（第三张图），立刻跳回中间（第二张图）
        else if currentOffsetX == view.bounds.width * 2 {
            scrollView.setContentOffset(CGPoint(x: view.bounds.width, y: 0), animated: false)
        }
    }
    
    // 自动滚动的方法（可选）
    private func startAutoScroll() {
        Timer.scheduledTimer(withTimeInterval: 3, repeats: true) { [weak self] _ in
            guard let self = self else { return }
            let nextOffsetX = self.scrollView.contentOffset.x + self.view.bounds.width
            self.scrollView.setContentOffset(CGPoint(x: nextOffsetX, y: 0), animated: true)
        }
    }
}

这种方法既支持手动滑动，也可以加上自动滚动的逻辑，灵活度更高

两种方法都能实现你要的连续滚动效果，你可以根据自己的需求来选，要是在实现过程中遇到细节问题，随时来问！

内容的提问来源于stack exchange，提问作者Bartłomiej Janczak