尝试SchedulerBinding,

 SchedulerBinding.instance
                .addPostFrameCallback((_) => setState(() {
              isDataFetched = true;
            }));

我的英语很差 原谅我

import 'package:flutter/material.dart';

class TestBox extends StatefulWidget {
  final Color color;
  final Duration delay;

  const TestBox({
    Key? key,
    this.color = Colors.red,
    this.delay = const Duration(seconds: 5),
  }) : super(key: key);

  @override
  _TestBoxState createState() => _TestBoxState();
}

class _TestBoxState extends State<TestBox> {
  String? label;

  @override
  void initState() {
    initialMembers();
    super.initState();
  }

  void initialMembers() async {
    label = await fetchLabel();

    if (mounted) setState(() {});

    /// don't worry
    /// if `(!mounted)`, means wen `build` calld
    /// the label already has the newest value
  }

  Future<String> fetchLabel() async {
    await Future.delayed(widget.delay);
    print('fetchLabel call');
    return 'from fetchLabel()';
  }

  @override
  Widget build(BuildContext context) {
    return AnimatedContainer(
      margin: EdgeInsets.symmetric(vertical: 12),
      duration: Duration(milliseconds: 500),
      width: 220,
      height: 120,
      color: label == null ? Colors.white : widget.color,
      child: Center(
        child: Text(label ?? 'fetching...'),
      ),
    );
  }
}

Column(
  children: [
    TestBox(
      delay: Duration(seconds: 1),
      color: Colors.green,
    ),
    TestBox(
      delay: Duration(seconds: 3),
      color: Colors.yellow,
    ),
    TestBox(
      delay: Duration(seconds: 5),
      color: Colors.red,
    ),
  ],
),

你可以用

https://github.com/slightfoot/flutter_after_layout

它只在布局完成后执行一次函数。 或者只是看看它的实现，并将其添加到你的代码中:-)

基本上就是

  void initState() {
    super.initState();
    WidgetsBinding.instance
        .addPostFrameCallback((_) => yourFunction(context));
  }

PostFrameCallback在屏幕完全绘制之前触发。因此，Devv上面的回答有助于添加延迟以允许屏幕绘制。

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) {
       Future.delayed(Duration(seconds: 3), () => yourFunction());
    });
  }

我有一个有状态的小部件，我使用html_editor_enhanced插件小部件。这是在其中设置初始消息的唯一方法。

class _SendChatMessageState extends State<SendChatMessage> {
  final _htmlController = HtmlEditorController();

      @override
      void initState() {
        super.initState();
    
          Future.delayed(const Duration(seconds: 3), () {
            _htmlController.setText(widget.chatMessage.message ?? '');
          });
      }

我尝试了addPostFrameCallback，但它不起作用，因为JavaScript生成异常“HTML编辑器仍在加载，请在评估此JS之前等待…”

有三种可能的方法:

1) WidgetsBinding.instance.addPostFrameCallback((_) => yourFunc(context));

2) Future.delayed(Duration.zero, () => yourFunc(context));

3) Timer.run(() => yourFunc(context));

至于context，在渲染完所有的小部件后，我需要在Scaffold.of(context)中使用它。

但在我看来，最好的办法是:

void main() async {
  WidgetsFlutterBinding.ensureInitialized(); //all widgets are rendered here
  await yourFunc();
  runApp( MyApp() );
}