flutter中使用命名路由跳转时传参（pushNamed）并在

当我使用routes属性定义命名路由，并通过下列方法进行携带arguments参数进行跳转

Navigator.pushNamed(
      context,
      routeName,
      arguments: <args>,
);

然而，当我在initState中通过下列方式接收参数时，debug console中出现了报错

@override
void initState() {
  args = ModalRoute.of(context).settings.arguments;
}

报错内容如下

20:49:44.129 4 info flutter.tools I/flutter ( 2680): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
20:49:44.129 5 info flutter.tools I/flutter ( 2680): The following assertion was thrown building Builder:
20:49:44.129 6 info flutter.tools I/flutter ( 2680): inheritFromWidgetOfExactType(_ModalScopeStatus) or inheritFromElement() was called before
20:49:44.130 7 info flutter.tools I/flutter ( 2680): _CourseCohortScreenState.initState() completed.
20:49:44.130 8 info flutter.tools I/flutter ( 2680): When an inherited widget changes, for example if the value of Theme.of() changes, its dependent
20:49:44.131 9 info flutter.tools I/flutter ( 2680): widgets are rebuilt. If the dependent widget's reference to the inherited widget is in a constructor
20:49:44.131 10 info flutter.tools I/flutter ( 2680): or an initState() method, then the rebuilt dependent widget will not reflect the changes in the
20:49:44.131 11 info flutter.tools I/flutter ( 2680): inherited widget.
20:49:44.138 12 info flutter.tools I/flutter ( 2680): Typically references to inherited widgets should occur in widget build() methods. Alternatively,
20:49:44.138 13 info flutter.tools I/flutter ( 2680): initialization based on inherited widgets can be placed in the didChangeDependencies method, which
20:49:44.138 14 info flutter.tools I/flutter ( 2680): is called after initState and whenever the dependencies change thereafter.

后来google之后找到了解决办法（虽然目前的状态还是知其然不知其所以然）

1. 配置落地页的构建和参数调用逻辑：

//  login_page.dart
class LoginPage extends StatefulWidget {
  final String share_id;
  LoginPage({ Key key,  this.share_id }) : super(key: key);

  @override
  State<StatefulWidget> createState() => LoginPageState();
}

class LoginPageState extends  State<LoginPage> {

  @override
  void initState() {
    super.initState();
    getUserInfo(widget.user_id);    // 使用userId
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: Center(
        child: Text(
          'hello ${widget.user_id}',
          textScaleFactor: 5.0,
        ),
      ),
    );
  }
}

2. 在MaterialApp中使用onGenerateRoute属性来定义命名路由，在需要传入参数的Widget页面定义初始化变量，并在路由定义时传入变量：

// main.dart
import './pages/login_page.dart'    // 引用LoginPage
...
onGenerateRoute: (RouteSettings settings) {
  print('build route for ${settings.name}');
  var routes = <String, WidgetBuilder>{
    "login": (ctx) => LoginPage(settings.arguments),
    "other": (ctx) => SomeWidget(),
  };
  WidgetBuilder builder = routes[settings.name];
  return MaterialPageRoute(builder: (ctx) => builder(ctx));
},

3此时便可以调用相同的方法来实现路由跳转,并传入参数

Navigator.of(context).pushNamed("login", arguments: "IDXXXX");