NavigationController.pushviewController

@IBAction func goToGalleryBtn(_ sender: Any) {
        if UIImagePickerController.isSourceTypeAvailable(.photoLibrary){
            PHPhotoLibrary.requestAuthorization { (status) in
                switch status {
                case .authorized:
                    self.presentPhotoPickerController()
                    break
                case .notDetermined:
                    if status == PHAuthorizationStatus.authorized{
                        self.presentPhotoPickerController()
                    }
                case .restricted:
                    let alert = UIAlertController(title: "Photo Library Restricted", message: "Photo Library access is restricted and cannot be accessed.", preferredStyle: .alert)
                    let okAction = UIAlertAction(title: "OK", style: .default)
                    alert.addAction(okAction)
                    self.present(alert, animated: true)
                case .denied:
                    let alert = UIAlertController(title: "Photo Library Denied", message: "Photo Library access was previously denied. Please update your Settings if you wish to change this.", preferredStyle: .alert)
                    let goToSettingsAction = UIAlertAction(title: "Go to Settings", style: .default){(action) in
                        DispatchQueue.main.async {
                            let url = URL(string: UIApplication.openSettingsURLString)!
                            UIApplication.shared.open(url, options: [:])
                        }
                    }
                    let cancelAction = UIAlertAction(title: "Cancel", style: .cancel)
                    alert.addAction(goToSettingsAction)
                    alert.addAction(cancelAction)
                    self.present(alert, animated: true)
                }
            }
        }
    }

    @IBAction func cancelBtn(_ sender: Any) {
        dismiss(animated: true, completion: nil)
    }
}

extension UserAvatarViewController: UIImagePickerControllerDelegate, UINavigationControllerDelegate{
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        if let image = info[.editedImage] as? UIImage{
            imageGallery = image
        }else if let image = info[.originalImage] as? UIImage{
            imageGallery = image
        }
        dismiss(animated: true, completion: nil)

        let storyBoard: UIStoryboard = UIStoryboard(name: "HomeViewController", bundle: nil)
        let homeVC = storyBoard.instantiateViewController(withIdentifier: "HomeVC") as! HomeViewController
        homeVC.imageView = imageGallery
//        self.navigationController?.pushViewController(homeVC, animated: true)
        self.navigationController?.popViewController(animated: true)
    }

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