encapsulating the user code_9.swift

class ViewController: UIViewController
{
    @IBOutlet weak var avatarView: UIImageView!

    var api: API!

    @IBAction func changeAvatar(_ sender: UITapGestureRecognizer) {
        guard let senderView = sender.view else { fatalError("Tapped on viewless gesture recognizer?") }

        getImage(focusView: senderView).then { image -> Promise<UIImage> in
            guard let data = UIImageJPEGRepresentation(image, 0.8) else { throw JPEGRepresentationError.badImage }
            return self.api.upload(avatar: data).then { image }
        }
        .then { image in
            self.avatarView.image = image
        }
        .catch { error in
            guard error as? UserInteractionError != .userCanceled else { return }
            self.displayInformationAlert(title: "Error", message: error.localizedDescription)
        }
    }
}