在没有提前按下任何按钮事件的情况下，如何在获得生物认证结果为真后以编程方式获得页面转换？

Question

我正在用 flutter 实现的 local_auth 插件创建一个应用程序。我想要下面的流程。

1.background page(BioAuthScreen) is up
2.simultaneously authenticateWithBiometrics dialog is up.
3.if result is true, get the page transition to HomeScreen(folloing comment // 3),

如果我按下按钮（注释// 4 之后的代码），它的工作。（向上对话框，如果结果为真，页面转换OK）。但我不喜欢背景页面中的按钮。如果我将代码放在注释 // 1 或 // 2 之后，对话框就会打开，如果结果为真，但背景页面仍然存在。没有错误。

这是代码。

class BioAuthScreen extends StatefulWidget {
  BioAuthScreen({Key key, this.initFlag = false}) : super(key: key);
  final bool initFlag;

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

class _BioAuthScreenState extends State<BioAuthScreen>
    with WidgetsBindingObserver {
  final LocalAuthentication _localAuthentication = LocalAuthentication();
  bool _isAuthenticated;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    // 1
 /*   WidgetsBinding.instance.addPostFrameCallback((_) async {
      await _getAuthenticated();
    }); */
  }

  @override
  void didChangeDependencies() async {
    super.didChangeDependencies();
    await Future.delayed(const Duration(milliseconds: 700));
    // 2
    // await _getAuthenticated();
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    super.didChangeAppLifecycleState(state);
    if (state == AppLifecycleState.inactive) {
    } else if (state == AppLifecycleState.paused) {
      Navigator.pushReplacement(
          context, MaterialPageRoute(builder: (context) => BioAuthScreen()));
    } else if (state == AppLifecycleState.resumed) {}
  }

  Future<List<BiometricType>> _getListOfBiometricTypes() async {
    List<BiometricType> listOfBiometrics;
    try {
      listOfBiometrics = await _localAuthentication.getAvailableBiometrics();
    } on PlatformException catch (e) {
      print(e);
    }
    print(listOfBiometrics);
    return listOfBiometrics;
  }

  Future<void> _getAuthenticated() async {
    var result = false;
    var availableBiometricTypes = await _getListOfBiometricTypes();
    try {
      if (availableBiometricTypes.contains(BiometricType.face) ||
          availableBiometricTypes.contains(BiometricType.fingerprint)) {
        result = await _localAuthentication.authenticateWithBiometrics(
          localizedReason: '生体認証',
          useErrorDialogs: true,
          stickyAuth: false,
        );
      }
    } on PlatformException catch (e) {
      print(e);
    }
    if (!mounted) return;
    print('result: $result');
    // 3
    if (result) {
      await Navigator.pushNamed(context, Constants.homeScreenRoute);
    }
  }

  @override
  Widget build(BuildContext context) {
    final screenWidth = MediaQuery.of(context).size.width;
    final screenHeight = MediaQuery.of(context).size.height;
    return SafeArea(
      child: Scaffold(
        body: FractionallySizedBox(
          widthFactor: 1,
          heightFactor: 1,
          child: DecoratedBox(
            decoration: const BoxDecoration(
              color: CustomColors.midBlue,
            ),
            child: Column(
              mainAxisAlignment: MainAxisAlignment.start,
              children: <Widget>[
                const Padding(
                  padding: EdgeInsets.all(40.0),
                ),
                // Title
                AuthTitleComponent(),
                SizedBox(height: screenHeight * 0.28),
                ButtonTheme(
                  minWidth:
                      screenWidth > 600 ? screenWidth * 0.6 : screenWidth * 0.7,
                  height: 45,
                  child: RaisedButton(
                    elevation: 3.0,
                    color: CustomColors.lightBlue,
                    // 4
                    onPressed: () async {
                      await _getAuthenticated();
                    },
                    child: Text(
                      'BioMetricAuthLogin',
                      style: Theme.of(context)
                          .textTheme
                          .headline2
                          .copyWith(color: Colors.white),
                    ),
                  ),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}

Answer 1

我能够使用您提供的代码片段复制报告的行为。当通过 didChangeAppLifecycleState.

调用生物识别身份验证时，LocalAuthentication.authenticate 捕获 PlatformException

这似乎是一个错误，我已将其作为问题提交 here。我使用的是 Flutter 2.0.0 稳定版和 local_auth 1.1.0 作为参考。

在没有提前按下任何按钮事件的情况下，如何在获得生物认证结果为真后以编程方式获得页面转换？

How Can I get a page transition programmatically after getting biometric authentication result true without any button press event in advance?

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