flutter flutter_screenutil Looking up a deactivated widget's ancestor is unsafe.

先强调一下，很多问题可以使用reStart更新试一下下!!!!!

使用flutter_screenutil 报错 Looking up a deactivated widget‘s ancestor is unsafe.

The following assertion was thrown while dispatching notifications for SwiperController:
Looking up a deactivated widget‘s ancestor is unsafe.
At this point the state of the widget‘s element tree is no longer stable.
To safely refer to a widget‘s ancestor in its dispose() method, save a reference to the ancestor
by
calling dependOnInheritedWidgetOfExactType() in the widget‘s didChangeDependencies() method.

为SwipController发送通知时引发了以下断言：

查找停用小部件的祖先是不安全的。

此时，小部件元素树的状态不再稳定。

要在dispose（）方法中安全地引用小部件的祖先，请保存对祖先的引用

通过

在小部件的didChangeDependencies（）方法中调用dependOnInheritedWidgetOfExactType（）。

初始代码，这个组件引用到了ListView里，开始报错

经过仔细阅读使用文档，核对版本号

新版本代码如下

首先要在lib/main.dart注册一下

import ‘package:flutter/material.dart‘;
import ‘pages/tabs/Tabs.dart‘;
// import ‘routers/router.dart‘;
import ‘pages/tabs/Tabs.dart‘;
import ‘pages/test/Search.dart‘;
import ‘package:flutter_screenutil/flutter_screenutil.dart‘;

void main() {
  runApp(MyApp());
}

// 输入stf  有状态组件
// stss 无状态组件
class MyApp extends StatefulWidget {
  const MyApp({Key? key}) : super(key: key);

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

class _MyAppState extends State {
  final Map routes = {
    ‘/‘: (context) => Tabs(),
    ‘/search‘: (context) => SearchPage(),
  };

  Route _onGenerateRoute(RouteSettings settings) {
    //   return MaterialPageRoute(builder: (context) {
    // 如果访问的路由页需要登录，但当前未登录，则直接返回登录页路由，
    // 引导用户登录；其它情况则正常打开路由。
    // 统一处理
    // })
    final String? name = settings.name;
    final Function pageContentBuilder = routes[name] as Function;
    print(‘到1‘);
    if (settings.arguments != null) {
      print(‘到2‘);
      final Route route = MaterialPageRoute(
          builder: (context) =>
              pageContentBuilder(context, arguments: settings.arguments));
      return route;
    } else {
      print(‘到3‘);
      final Route route =
          MaterialPageRoute(builder: (context) => pageContentBuilder(context));
      return route;
    }
  }

  @override
  Widget build(BuildContext context) {
    // return MaterialApp(
    //   // home: Tabs()
    //   initialRoute: ‘/‘,
    //   onGenerateRoute: _onGenerateRoute,
    // );
    return ScreenUtilInit(
      designSize: Size(360, 690),
      builder: () => MaterialApp(
        // home: Tabs()
        initialRoute: ‘/‘,
        onGenerateRoute: _onGenerateRoute,
      ),
    );
  }
}

使用案例

Widget _titleWidget(value) {
    return Container(
      height: 32.h,
      margin: EdgeInsets.only(left: 20.w),
      padding: EdgeInsets.only(left: 20.w),
      decoration: BoxDecoration(
          border: Border(left: BorderSide(color: Colors.red, width: 10.w))),
      child: Text(value, style: TextStyle(color: Colors.pink)),
    );
  }

最需要注意的一点点！！！！使用reStart更新试一下下!!!!!

大功告成

原文：https://www.cnblogs.com/sugartang/p/15260798.html