它不是那么简单，但是正如Rob所提到的，您可以保存照片资产url，然后使用Photos框架来获取它。您可以使用PHImageManager方法requestImageData获取它们。

import UIKit
import Photos
class ViewController: UIViewController, UINavigationControllerDelegate, UIImagePickerControllerDelegate {
    @IBOutlet weak var imageView: UIImageView!
    let galleryPicker = UIImagePickerController()
    // create a method to fetch your photo asset and return an UIImage on completion
    override func viewDidLoad() {
        super.viewDidLoad()
        // lets add a selector to when the user taps the image
        imageView.isUserInteractionEnabled = true
        imageView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(openPicker)))
        // request authorization
        switch PHPhotoLibrary.authorizationStatus() {
        case .authorized:
            print("The user has explicitly granted your app access to the photo library.")
            return
        case .denied:
            print("The user has explicitly denied your app access to the photo library.")
        case .notDetermined:
            PHPhotoLibrary.requestAuthorization { status in
                print("status", status)
            }
        case .restricted:
            print("Your app is not authorized to access the photo library, and the user cannot grant such permission.")
        default: break
        }
    }
    // opens the image picker for photo library
    @objc func openPicker(_ gesture: UITapGestureRecognizer) {
        galleryPicker.sourceType = .photoLibrary
        galleryPicker.delegate = self
        present(galleryPicker, animated: true)
    }
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        self.imageView.contentMode = .scaleAspectFit
        // check if there is an url saved in the user defaults
        // and fetch its first object (PHAsset)
        if let assetURL = UserDefaults.standard.url(forKey: "assetURL") {
            if let asset = PHAsset.fetchAssets(withALAssetURLs: [assetURL], options: nil).firstObject {
                asset.asyncImageData { data, _, _, _ in
                    print("fetched")
                    guard let data = data else { return }
                    self.imageView.image = UIImage(data: data)
                }
            } else {
                print("assetURL:", assetURL)
                self.imageView.image = UIImage(contentsOfFile: assetURL.path)
            }
        } else {
            print("no assetURL found")
        }

    }
    func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
        dismiss(animated: true)
        print("canceled")
    }
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {

        self.imageView.image = info[.originalImage] as? UIImage
        if let phAsset = info[.phAsset] as? PHAsset {
            phAsset.asyncURL { url in
                guard let url = url else { return }
                UserDefaults.standard.set(url, forKey: "assetURL")
                print("assetURL saved")
            }
        }
        dismiss(animated: true)
    }
}

extension PHAsset {
    func asyncURL(_ completion: @escaping ((URL?) -> Void)) {
        switch mediaType {
        case .image:
            let options: PHContentEditingInputRequestOptions = .init()
            options.canHandleAdjustmentData = { _ in true }
            requestContentEditingInput(with: options) { editingInput, _ in
                completion(editingInput?.fullSizeImageURL)
            }
        case .video:
            let options: PHVideoRequestOptions = .init()
            options.version = .original
            PHImageManager.default()
                .requestAVAsset(forVideo: self, options: options) { asset, _, _ in
                completion((asset as? AVURLAsset)?.url)
            }
        default:
            completion(nil)
        }
    }
    func asyncImageData(version: PHImageRequestOptionsVersion = .original, completion: @escaping  (Data?, String?, UIImage.Orientation, [AnyHashable : Any]?) -> ()) {
        let options = PHImageRequestOptions()
        options.version = version
        PHImageManager.default()
            .requestImageData(for: self, options: options, resultHandler: completion)
    }
}
extension URL {
    var phAsset: PHAsset? {
        PHAsset.fetchAssets(withALAssetURLs: [self], options: nil).firstObject
    }
}

注意：不要忘记编辑您的信息列表并添加“隐私-照片库使用说明”

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