如何在点击按钮时打开UIPageViewController

import UIKit

class ViewController: UIViewController, UIPageViewControllerDelegate, UIPageViewControllerDataSource {

    var pageViewController: UIPageViewController!

    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建UIPageViewController实例
        pageViewController = UIPageViewController(transitionStyle: .scroll, navigationOrientation: .horizontal, options: nil)
        pageViewController.delegate = self
        pageViewController.dataSource = self
        
        // 设置UIPageViewController的初始页面
        let initialViewController = getPageContentViewController(index: 0)
        pageViewController.setViewControllers([initialViewController], direction: .forward, animated: true, completion: nil)
        
        // 将UIPageViewController添加到当前视图控制器中
        addChild(pageViewController)
        view.addSubview(pageViewController.view)
        pageViewController.didMove(toParent: self)
        
        // 创建按钮并添加点击事件
        let button = UIButton(frame: CGRect(x: 100, y: 100, width: 200, height: 50))
        button.setTitle("打开UIPageViewController", for: .normal)
        button.addTarget(self, action: #selector(openPageViewController), for: .touchUpInside)
        view.addSubview(button)
    }
    
    // 点击按钮时打开UIPageViewController
    @objc func openPageViewController() {
        present(pageViewController, animated: true, completion: nil)
    }
    
    // 获取指定索引的页面内容视图控制器
    func getPageContentViewController(index: Int) -> UIViewController {
        let contentViewController = UIViewController()
        contentViewController.view.backgroundColor = UIColor.random // 设置页面背景颜色，这里使用了一个自定义的UIColor扩展方法
        return contentViewController
    }
    
    // UIPageViewControllerDataSource方法，提供页面内容
    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
        // 返回前一个页面的内容视图控制器
        guard let currentIndex = pageViewController.viewControllers?.first?.view.tag else {
            return nil
        }
        let previousIndex = currentIndex - 1
        return getPageContentViewController(index: previousIndex)
    }
    
    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
        // 返回后一个页面的内容视图控制器
        guard let currentIndex = pageViewController.viewControllers?.first?.view.tag else {
            return nil
        }
        let nextIndex = currentIndex + 1
        return getPageContentViewController(index: nextIndex)
    }
    
    // UIPageViewControllerDelegate方法，可选实现
    // 可以在这里处理页面切换完成后的逻辑
}

extension UIColor {
    static var random: UIColor {
        return UIColor(red: .random(in: 0...1), green: .random(in: 0...1), blue: .random(in: 0...1), alpha: 1.0)
    }
}