For UI that should differ slightly on iOS and Android, i.e. on different platforms, there must be a way to detect
Most "Flutter" answer is as follows:
import 'package:flutter/foundation.dart' show TargetPlatform;
//...
if(Theme.of(context).platform == TargetPlatform.android)
//do sth for Android
else if(Theme.of(context).platform == TargetPlatform.iOS)
//do sth else for iOS
else if(Theme.of(context).platform == TargetPlatform.fuchsia)
//even do sth else for Fuchsia OS