如何在页面加载时打开脚手架的抽屉?

您需要在第一帧加载后等待。

    _onLayoutDone(_) {
       //your logic here

    }

    @override
    void initState() {
      WidgetsBinding.instance.addPostFrameCallback(_onLayoutDone);
      super.initState();
    }

https://medium.com/@diegoveloper/flutter-widget-size-and-position-b0a9ffed9407

覆盖 initState .

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

  // use this
  Timer.run(() => Scaffold.of(context).openDrawer());
}

isDrawerBeingShown .

void _showDrawer(BuildContext context) async 它必须标记为异步,以便在生成方法之后运行。

创建 showDrawerUtility 方法在需要时按需显示抽屉。

编辑:

使用GlobalKey

GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey();


class MainScreen extends StatefulWidget {

  MainScreen({Key key }) : super(key: key);

  @override
  State<MainScreen> createState() => new MainScreenState();
}

class MainScreenState extends State<MainScreen> {
  bool isDrawerBeingShown;

  @override
  void initState() {
    super.initState();
    isDrawerBeingShown = false;
    _showDrawer(context);
  }

  void _showDrawer(BuildContext context) async {
    if(!isDrawerBeingShown) {
     _scaffoldKey.currentState.openDrawer();
      setState(() => isDrawerBeingShown = true);
    }
  }
 @override
  Widget build(BuildContext context) { // build method goes here}
}