在库比蒂诺路线之间导航无效

Question

我有一个使用Cupertino应用程序的简单应用程序。我在底部有四个标签，可让我在页面之间导航。在最后一个标签页AddCashPage上，我在页面上添加了按钮，这使我可以导航到第二页CalendarPage

该应用程序只有一页，所以我将发布整个内容

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
// import 'styles.dart';

import 'pages/summary_page.dart';
import 'pages/calendar_page.dart';
import 'pages/remove_cash_page.dart';


final scakey = new GlobalKey<_BottomState>();

class CashOnHandApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Cash on Hand',
      home: HomePage(),
    );
  }
}

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: CupertinoPageScaffold(
        navigationBar: CupertinoNavigationBar(
          middle: const Text('Cash on Hand'),
        ),
        child: Bottom(key: scakey),
      ),
    );
  }
}

class Bottom extends StatefulWidget {
  Bottom({Key key}) : super(key: key);

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

class _BottomState extends State<Bottom> {
  final myKey = new GlobalKey<_BottomState>();
  int _selectedIndex = 0;

  void _onItemTapped(int index) {
    setState(() {
      _selectedIndex = index;
      print(_selectedIndex);
    });
  }

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

  @override
  Widget build(BuildContext context) {
    return CupertinoTabScaffold(
      key: myKey,
      tabBar: CupertinoTabBar(
        onTap: _onItemTapped,
        items: const <BottomNavigationBarItem>[
          BottomNavigationBarItem(
            icon: Icon(CupertinoIcons.home),
            title: Text('Summary Page'),
          ),
          BottomNavigationBarItem(
            icon: Icon(CupertinoIcons.clock_solid),
            title: Text('Calendar'),
          ),
          BottomNavigationBarItem(
            icon: Icon(CupertinoIcons.minus_circled),
            title: Text('Remove Cash'),
          ),
          BottomNavigationBarItem(
            icon: Icon(CupertinoIcons.plus_circled),
            title: Text('Add Cash'),
          ),
        ],
      ),
      tabBuilder: (context, index) {
        switch (index) {
          case 0:
            return CupertinoTabView(builder: (context) {
              return CupertinoPageScaffold(
                child: SummaryPage(),
              );
            });
          case 1:
            return CupertinoTabView(builder: (context) {
              return CupertinoPageScaffold(
                child: CalendarPage(),
              );
            });
          case 2:
            return CupertinoTabView(builder: (context) {
              return CupertinoPageScaffold(
                child: RemoveCashPage(),
              );
            });
          case 3:
            return CupertinoTabView(builder: (context) {
              return CupertinoPageScaffold(
                child: AddCashPage(),
              );
            });
        }
      },
    );
  }
}

class AddCashPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Container(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          CupertinoButton(
            onPressed: () {
              scakey.currentState._onItemTapped(1);
            },
            child: Text('data'),
          ),
        ],
      ),
    );
  }
}

我以前可以在材料应用程序上使用scakey.currentState._onItemTapped(1);，所以我认为它在Cupertino应用程序上也可以使用

Answer 1

根据官方文件https://api.flutter.dev/flutter/cupertino/CupertinoTabScaffold/tabBar.html 提供其他CupertinoTabBar.currentIndex不会影响支架或标签栏的活动标签索引。要以编程方式更改活动标签的索引，请使用CupertinoTabController。
您需要使用标签页控制器

代码段

final CupertinoTabController _controller = CupertinoTabController();

  void _onItemTapped(int index) {
    setState(() {
      _selectedIndex = index;
      _controller.index = index;
      print(_selectedIndex);
    });
  }

工作演示

完整代码

import 'package:flutter/material.dart';
import 'package:flutter/cupertino.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: HomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: Column(
          // Column is also a layout widget. It takes a list of children and
          // arranges them vertically. By default, it sizes itself to fit its
          // children horizontally, and tries to be as tall as its parent.
          //
          // Invoke "debug painting" (press "p" in the console, choose the
          // "Toggle Debug Paint" action from the Flutter Inspector in Android
          // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
          // to see the wireframe for each widget.
          //
          // Column has various properties to control how it sizes itself and
          // how it positions its children. Here we use mainAxisAlignment to
          // center the children vertically; the main axis here is the vertical
          // axis because Columns are vertical (the cross axis would be
          // horizontal).
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}



final scakey = new GlobalKey<_BottomState>();

class CashOnHandApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Cash on Hand',
      home: HomePage(),
    );
  }
}

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: CupertinoPageScaffold(
        navigationBar: CupertinoNavigationBar(
          middle: const Text('Cash on Hand'),
        ),
        child: Bottom(key: scakey),
      ),
    );
  }
}

class Bottom extends StatefulWidget {
  Bottom({Key key}) : super(key: key);

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

class _BottomState extends State<Bottom> {
  final myKey = new GlobalKey<_BottomState>();
  int _selectedIndex = 0;
  final CupertinoTabController _controller = CupertinoTabController();

  void _onItemTapped(int index) {
    setState(() {
      _selectedIndex = index;
      _controller.index = index;
      print(_selectedIndex);
    });
  }

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

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return CupertinoTabScaffold(
      controller: _controller,
      key: myKey,
      tabBar: CupertinoTabBar(
        onTap: _onItemTapped,
        items: const <BottomNavigationBarItem>[
          BottomNavigationBarItem(
            icon: Icon(CupertinoIcons.home),
            title: Text('Summary Page'),
          ),
          BottomNavigationBarItem(
            icon: Icon(CupertinoIcons.clock_solid),
            title: Text('Calendar'),
          ),
          BottomNavigationBarItem(
            icon: Icon(CupertinoIcons.minus_circled),
            title: Text('Remove Cash'),
          ),
          BottomNavigationBarItem(
            icon: Icon(CupertinoIcons.plus_circled),
            title: Text('Add Cash'),
          ),
        ],
      ),
      tabBuilder: (context, index) {
        switch (index) {
          case 0:
            return CupertinoTabView(builder: (context) {
              return CupertinoPageScaffold(
                child: SummaryPage(),
              );
            });
          case 1:
            return CupertinoTabView(builder: (context) {
              return CupertinoPageScaffold(
                child: CalendarPage(),
              );
            });
          case 2:
            return CupertinoTabView(builder: (context) {
              return CupertinoPageScaffold(
                child: RemoveCashPage(),
              );
            });
          case 3:
            return CupertinoTabView(builder: (context) {
              return CupertinoPageScaffold(
                child: AddCashPage(),
              );
            });
        }
      },
    );
  }
}

class AddCashPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Container(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          CupertinoButton(
            onPressed: () {
              scakey.currentState._onItemTapped(1);
            },
            child: Text('data'),
          ),
        ],
      ),
    );
  }
}

class SummaryPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text("Summary");
  }
}

class CalendarPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text("Calendar");
  }
}

class RemoveCashPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text("RemoveCash");
  }
}