如何使UIScrollview一次只显示一个子视图

import UIKit

class ViewController: UIViewController, UIScrollViewDelegate {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let scrollView = UIScrollView(frame: CGRect(x: 0, y: 0, width: view.frame.width, height: view.frame.height))
        scrollView.contentSize = CGSize(width: view.frame.width * 3, height: view.frame.height)
        scrollView.isPagingEnabled = true
        scrollView.delegate = self
        
        let view1 = UIView(frame: CGRect(x: 0, y: 0, width: view.frame.width, height: view.frame.height))
        view1.backgroundColor = UIColor.red
        scrollView.addSubview(view1)
        
        let view2 = UIView(frame: CGRect(x: view.frame.width, y: 0, width: view.frame.width, height: view.frame.height))
        view2.backgroundColor = UIColor.green
        scrollView.addSubview(view2)
        
        let view3 = UIView(frame: CGRect(x: view.frame.width * 2, y: 0, width: view.frame.width, height: view.frame.height))
        view3.backgroundColor = UIColor.blue
        scrollView.addSubview(view3)
        
        view.addSubview(scrollView)
    }
    
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        // 在这里可以监听滚动事件，执行相应的操作
    }
}