同步两个NSScrollView

import Cocoa

class ViewController: NSViewController {

    @IBOutlet weak var scrollView1: NSScrollView!
    @IBOutlet weak var scrollView2: NSScrollView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 监听scrollView1的滚动事件
        scrollView1.contentView.postsBoundsChangedNotifications = true
        NotificationCenter.default.addObserver(self, selector: #selector(scrollView1DidScroll), name: NSView.boundsDidChangeNotification, object: scrollView1.contentView)
        
        // 监听scrollView2的滚动事件
        scrollView2.contentView.postsBoundsChangedNotifications = true
        NotificationCenter.default.addObserver(self, selector: #selector(scrollView2DidScroll), name: NSView.boundsDidChangeNotification, object: scrollView2.contentView)
    }
    
    // 当scrollView1滚动时，更新scrollView2的滚动位置
    @objc func scrollView1DidScroll() {
        scrollView2.contentView.scroll(to: scrollView1.contentView.bounds.origin)
    }
    
    // 当scrollView2滚动时，更新scrollView1的滚动位置
    @objc func scrollView2DidScroll() {
        scrollView1.contentView.scroll(to: scrollView2.contentView.bounds.origin)
    }
}