Comparing Flutter microtasks and post-frame callbacks

A microtask and a post-frame callback do not express the same timing requirement. This older experiment scheduled both during initState and logged dependency changes:

@override
void initState() {
  super.initState();
  print('init');
  Future<dynamic>.microtask(() {
    print('after init with micro task');
  });

  SchedulerBinding.instance.addPostFrameCallback((_) {
    print('after init with scheduler binding');
  });

  WidgetsBinding.instance.addPostFrameCallback((_) {
    print('after init with widgets binding');
  });
}

@override
void didChangeDependencies() {
  super.didChangeDependencies();
  print('didChangeDependencies');
}

The earlier run recorded:

flutter: init
flutter: didChangeDependencies
flutter: build
flutter: after init with micro task
flutter: after init with scheduler binding
flutter: after init with widgets binding

The trace is an observation from that application. A post-frame callback relates work to a completed frame; it does not prove that every asynchronous initialization task has finished. A microtask is not a general replacement for waiting for layout.

Choose the boundary the operation actually requires, and avoid scheduling the same one-time effect on every rebuild. No lifecycle trace was regenerated for this revision.

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