Note:
  Add custom iOS code to your own existing application’s
  project or to a plugin, not to the module’s .ios/
  directory. Changes made in your module’s .ios/
  directory do not appear in your existing iOS project
  using the module, and may be overwritten by Flutter.

Do not source control the .ios/ directory since it’s autogenerated.
  Before building the module on a new machine, run flutter pub get
  in the my_flutter directory first to regenerate the .ios/
  directory before building iOS project using the Flutter module.

Embed the Flutter module in your existing application

After you have developed your Flutter module,
you can embed it using the methods described at the top of the page.

Note:
  You can run in Debug mode on a simulator or a real device,
  and Release on a real device. Learn more about
  Flutter’s build modes