在swift中从库中选择照片不起作用

import Photos

PHPhotoLibrary.requestAuthorization { status in
    if status == .authorized {
        // 用户已授权访问相册，可以进行照片选择操作
    } else {
        // 用户未授权访问相册，需要提示用户授权
    }
}

import UIKit

class ViewController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    
    let imagePicker = UIImagePickerController()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        imagePicker.sourceType = .photoLibrary
        imagePicker.delegate = self
    }
    
    // 选择照片按钮点击事件
    @IBAction func selectPhotoButtonTapped(_ sender: UIButton) {
        present(imagePicker, animated: true, completion: nil)
    }
    
    // UIImagePickerControllerDelegate方法，处理选择的照片
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        if let selectedImage = info[.originalImage] as? UIImage {
            // 处理选择的照片
        }
        
        dismiss(animated: true, completion: nil)
    }
}