[UIImagePickerController sample] #iOS

info.plist

<plist version="1.0">
<dict>
    ...
	<key>NSPhotoLibraryUsageDescription</key>
	<string>TODO: Write the purpose of the library</string>
    ...
</dict>
</plist>

ViewController.swift

import UIKit
import Photos

class ViewController: UIViewController {
  
  override func viewDidLoad() {
    super.viewDidLoad()
  }
  
    private func selectFromLibrary() {
        let status = PHPhotoLibrary.authorizationStatus()
        switch status {
        case .authorized:
            showImagePicker()
        case .notDetermined:
            PHPhotoLibrary.requestAuthorization { status in
                if case .authorized = status {
                    self.showImagePicker()
                }
            }
        case .denied, .restricted:
            break
        @unknown default:
            break
        }
    }

    private func showImagePicker() {
        let imagePicker = UIImagePickerController()
        imagePicker.delegate = self
        imagePicker.sourceType = .photoLibrary

        // Change navigation bar style if needed.
        // imagePicker.navigationBar.isTranslucent = false
        // imagePicker.navigationBar.barTintColor = UIColor.black
        // imagePicker.navigationBar.tintColor = UIColor.white

        self.present(imagePicker, animated: true, completion: nil)
    }
}

extension ViewController: UIImagePickerControllerDelegate, UINavigationControllerDelegate {

    // MARK: - ImagePickerControllerDelegate
    func imagePickerController(_ picker: UIImagePickerController,
                               didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey: Any]) {
        picker.dismiss(animated: true, completion: {
            if let image = info[UIImagePickerController.InfoKey.originalImage] as? UIImage {

                // Do something...
                picker.dismiss(animated: true, completion: nil)
            }
        })
    }

    func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
        picker.dismiss(animated: true, completion: nil)
    }

    // MARK: - UINavigationControllerDelegate
    func navigationController(_ navigationController: UINavigationController,
                              didShow viewController: UIViewController, animated: Bool) {
        viewController.navigationItem.title = "TITLE" // If needed.
    }
}