AVFoundationHelper.swift

import AVFoundation

enum CameraStatus {
    case notDetermined
    case restricted
    case denied
    case authorized
}

protocol AVFoundationHelperProtocol: AnyObject {
    // MARK: - Check and Respond to Camera Authorization Status

    var authorizationStatus: CameraStatus { get }

    // MARK: - Request Camera Permission

    func requestAccess(completionHandler handler: @escaping (Bool) -> Void)
}

final class AVFoundationHelper: AVFoundationHelperProtocol {
    // MARK: - Check and Respond to Camera Authorization Status

    var authorizationStatus: CameraStatus {
        let cameraAuthorizationStatus = AVCaptureDevice.authorizationStatus(for: .video)
        switch cameraAuthorizationStatus {
        case .notDetermined:
            return CameraStatus.notDetermined
        case .authorized:
            return CameraStatus.authorized
        case .restricted:
            return CameraStatus.restricted
        case .denied:
            return CameraStatus.denied
        @unknown default:
            return CameraStatus.notDetermined
        }
    }

    // MARK: - Request Camera Permission

    func requestAccess(completionHandler handler: @escaping (Bool) -> Void) {
        AVCaptureDevice.requestAccess(for: .video, completionHandler: { accessGranted in
            handler(accessGranted)
        })
    }
}


import UIKit

final class ViewController: UIViewController {
    @IBOutlet var cameraAccessButton: UIButton!
    @IBOutlet var photoImageView: UIImageView!

    private var model: AVFoundationHelperProtocol = AVFoundationHelper()

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    @IBAction func cameraButtonPressed(_: Any) {
        let status = model.authorizationStatus
        switch status {
        case .notDetermined:
            model.requestAccess { hasAccess in
                if hasAccess {
                    DispatchQueue.main.async {
                        self.showCameraReader()
                    }
                } else {
                    self.alertCameraAccessNeeded()
                }
            }
        case .restricted, .denied:
            alertCameraAccessNeeded()

        case .authorized:
            showCameraReader()
        }
    }

    private func alertCameraAccessNeeded() {
        let appName = "This app Name"

        let alert = UIAlertController(title: "This feature requires Camera Access",
                                      message: "In iPhone settings, tap \(appName) and turn on Camera access",
                                      preferredStyle: UIAlertController.Style.alert)

        let actionSettings = UIAlertAction(title: "Settings", style: .default, handler: { _ -> Void in
            guard let settingsAppURL = URL(string: UIApplication.openSettingsURLString) else { return }
            UIApplication.shared.open(settingsAppURL)
        })

        let actionCancel = UIAlertAction(title: "Cancel", style: .destructive, handler: { _ -> Void in
        })

        alert.addAction(actionSettings)
        alert.addAction(actionCancel)

        present(alert, animated: true, completion: nil)
    }
}

extension ViewController: UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    private func showCameraReader() {
        if UIImagePickerController.isSourceTypeAvailable(.camera) {
            let imagePicker = UIImagePickerController()
            imagePicker.sourceType = .camera
            imagePicker.allowsEditing = true
            imagePicker.delegate = self
            present(imagePicker, animated: true)

        } else if UIImagePickerController.isSourceTypeAvailable(.photoLibrary) {
            let imagePicker = UIImagePickerController()
            imagePicker.sourceType = .photoLibrary
            imagePicker.allowsEditing = true
            imagePicker.delegate = self
            present(imagePicker, animated: true)

        } else {
            // TODO: Implement proper alert
            alertCameraAccessNeeded()
        }
    }

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

        guard let image = info[.editedImage] as? UIImage else {
            print("No image found")
            return
        }
        photoImageView.image = image
        // print out the image size as a test
        print(image.size)
    }
}