在UIDocumentInteractionController中以编程方式滚动pdf

import UIKit

class ViewController: UIViewController, UIDocumentInteractionControllerDelegate {
    
    var documentInteractionController: UIDocumentInteractionController!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建UIDocumentInteractionController对象
        documentInteractionController = UIDocumentInteractionController(url: URL(fileURLWithPath: "path_to_pdf_file"))
        documentInteractionController.delegate = self
        
        // 显示pdf文件的预览界面
        documentInteractionController.presentPreview(animated: true)
        
        // 获取pdf预览界面中的UIScrollView对象
        if let scrollView = documentInteractionController.previewController?.view.subviews.first as? UIScrollView {
            // 设置contentOffset来滚动pdf
            scrollView.contentOffset = CGPoint(x: 0, y: 100) // 滚动到y轴偏移100的位置
        }
    }
    
    // UIDocumentInteractionControllerDelegate方法
    func documentInteractionControllerViewControllerForPreview(_ controller: UIDocumentInteractionController) -> UIViewController {
        return self
    }
}