Here is what I generally do when converting Objective C apps to Flutter:
1) Compile the current code you have with Xcode 13.1 (the latest version I am now using)
That will give me an insight into what the app does, what is the flow of screens, the user’s journey and so on. Will actually serve as a wire frame to look up to.
2) Files and Conversions
The next task is to change file name all to lowercase characters as that is not acceptable on Android.
3) Converting Images
After that, transposing iOS images with their @ chars into images acceptable to Flutter (there is a well defined procedure but it does take some time and effort).
4) Form the project in Flutter
At this step we would have all the files that the app needs in shape and form that the Flutter can use.
5) Screen by Screen Conversion
If you want to change something, upgrade the app, use new API calls etc this would be the time and place to do it.
The good news is that I have ton of codes in Flutter for all of the mundane tasks such as user registration, log in, log out, menus and so on. It is more of a customizing process instead of developing everything from scratch just for your project.
I would send you a new version of the once a day or at least 2-3 time a week, depending on various factors. I expect you to actively take part in this phase and guide the development process to the end.
7) Opening Accounts or Using the Existing Accounts on Google Play and the App Store.
I need to have access to the App Store Connect to get the sertificates for development and distribution.
8) Preparing Listing For the aAp
You would have one for the existing app, obviously, but expect things to change and that should be reflected in the listing right away.
9) Submitting the App to the Stores
This is as far as I go — I cannot guarantee that the app will be accepted but if there are problems, I will stay with you and change the app so that it can be published.