IOS Swift，如何检测文件上传点击UIWebView内部打开照片上传对话框

import UIKit
import WebKit

class ViewController: UIViewController, UIWebViewDelegate, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    
    var webView: UIWebView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建UIWebView对象
        webView = UIWebView(frame: view.bounds)
        webView.delegate = self
        
        // 添加到视图层级
        view.addSubview(webView)
        
        // 加载网页
        let url = URL(string: "https://example.com")
        let request = URLRequest(url: url!)
        webView.loadRequest(request)
    }
    
    func webView(_ webView: UIWebView, shouldStartLoadWith request: URLRequest, navigationType: UIWebView.NavigationType) -> Bool {
        // 判断是否为文件上传请求
        if let url = request.url, let httpMethod = request.httpMethod, httpMethod == "POST" {
            if url.absoluteString.contains("upload") {
                // 执行JavaScript代码，调用原生方法打开照片上传对话框
                webView.stringByEvaluatingJavaScript(from: "openPhotoPicker();")
                return false
            }
        }
        return true
    }
    
    func openPhotoPicker() {
        let imagePicker = UIImagePickerController()
        imagePicker.delegate = self
        imagePicker.sourceType = .photoLibrary
        present(imagePicker, animated: true, completion: nil)
    }
    
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        // 获取用户选择的照片
        let image = info[.originalImage] as! UIImage
        
        // 执行上传操作
        // ...
        
        // 关闭照片选择器
        picker.dismiss(animated: true, completion: nil)
    }
}