All code resides in the /lib folder: there's no Android / iOS specific code needed.
The article, slides and how this came to be, is here.
A sample app for our internal company talk about Flutter.
The end result looks a little something like this:
.gitignore
.DS_Store
.atom/
.idea
.packages
.pub/
build/
ios/.generated/
packages
pubspec.lock
.flutter-plugins
Author: CodemateLtd
Source: https://github.com/CodemateLtd /FlutterMates
License: MIT license