class SampleViewController: UIViewController {
    /// ボタンタップでカメラを起動する
    @IBAction private func startCamera() {
        // 1. カメラのアクセス権限確認
        self.confirmCameraAuthorizationStatus { isAuthorized in
            if isAuthorized {
                let sourceType = UIImagePickerController.SourceType.camera
                guard UIImagePickerController.isSourceTypeAvailable(sourceType) else {
                    return
                }

                // 2. UIImagePickerController のインスタンス生成、カメラ起動
                let cameraPicker = UIImagePickerController()
                cameraPicker.sourceType = sourceType
                cameraPicker.delegate = self
                self.present(cameraPicker, animated: true, completion: nil)
            }
        }
    }

    /// カメラの利用許可確認
    private func confirmCameraAuthorizationStatus(result: @escaping (Bool) -> Void) {
        // カメラの利用が許可されているか確認
        switch AVCaptureDevice.authorizationStatus(for: .video) {
        case .authorized:
            result(true)
        case .notDetermined:
            AVCaptureDevice.requestAccess(for: mediaType) { isGranted in
                DispatchQueue.main.async {
                    result(isGranted)
                }
            }
        case .denied, .restricted:
            result(false)
        @unknown default:
            result(false)
        }
    }
}

extension SampleViewController: UIImagePickerControllerDelegate {
    // 3. Delegateで撮影した写真を受け取る
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        guard let pickedImage = info[.originalImage] as? UIImage else {
            print("写真取得失敗")
            picker.dismiss(animated: true, completion: nil)
            return
        }

        picker.dismiss(animated: true, completion: nil)
        // pickedImageを使って何か処理をする
    }
}

extension MenuViewController: UINavigationControllerDelegate {    
}