UIImagePickerController避免在拍摄照片后使用/重试视图而不禁用其他控件

class ViewController: UIViewController, UIImagePickerControllerDelegate {

    // ...

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)

        hideShowCamera()
    }

    private func hideShowCamera() {
        if showCameraButton.isHidden {
            showCameraButton.isHidden = false
            imagePicker.delegate = self
            imagePicker.sourceType = .camera
            showCameraButton.setTitle("Hide Camera", for: .normal)
        } else {
            showCameraButton.isHidden = true
            imagePicker.delegate = nil
            imagePicker.sourceType = .camera
            showCameraButton.setTitle("Show Camera", for: .normal)
        }
    }

    // ...
}