两个UIScrollViews,同步滚动

class ViewController: UIViewController, UIScrollViewDelegate {
    // ...
}

class ViewController: UIViewController, UIScrollViewDelegate {
    let scrollView1 = UIScrollView()
    let scrollView2 = UIScrollView()

    override func viewDidLoad() {
        super.viewDidLoad()

        scrollView1.delegate = self
        scrollView2.delegate = self

        // ...
    }
}

class ViewController: UIViewController, UIScrollViewDelegate {
    // ...

    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        if scrollView == scrollView1 {
            scrollView2.contentOffset = scrollView.contentOffset
        } else if scrollView == scrollView2 {
            scrollView1.contentOffset = scrollView.contentOffset
        }
    }
}