问弹出窗口不会请求iOS 12中的相机访问权限

EN

if UIImagePickerController.isSourceTypeAvailable(.camera) {
   checkCameraAccess(isAllowed: {
            if $0 {
                DispatchQueue.main.async {
                    self.presentCamera()
                }
            } else {
                DispatchQueue.main.async {
                self.presentCameraSettings()
            }
        }
    })
}

func checkCameraAccess(isAllowed: @escaping (Bool) -> Void) {
    switch AVCaptureDevice.authorizationStatus(for: .video) {
    case .denied:
        isAllowed(false)
    case .restricted:
        isAllowed(false)
    case .authorized:
        isAllowed(true)
    case .notDetermined:
        AVCaptureDevice.requestAccess(for: .video) { isAllowed($0) }
    }
}

private func presentCamera() {
    let imagePicker = UIImagePickerController()
    imagePicker.delegate = self
    imagePicker.sourceType = .camera
    present(imagePicker, animated: true, completion: nil)
}

private func presentCameraSettings() {
    let alert = UIAlertController.init(title: "allowCameraTitle", message: "allowCameraMessage", preferredStyle: .alert)
    alert.addAction(UIAlertAction.init(title: "Cancel", style: .cancel, handler: { (_) in
    }))

    alert.addAction(UIAlertAction.init(title: "Settings", style: .default, handler: { (_) in
        UIApplication.shared.open(URL(string: UIApplication.openSettingsURLString)!, options: [:], completionHandler: nil)
    }))

    present(alert, animated: true)
}