Flutter setState() 不触发重建

Question

我有一个登录页面，我想在点击按钮时将其更改为 CupertinoActivityIndicator。这是我的代码：

class AuthRegister extends StatefulWidget {
  AuthRegister({Key key, this.authenticator}): super(key: key);

  final FirebaseAuth authenticator;

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

class _AuthRegisterState extends State<AuthRegister> {

  final _formKey = GlobalKey<FormState>();
  final _emailController = TextEditingController();
  final _passwordController = TextEditingController();

  bool _loading = false;


  void _register(context) async {
    setState(() {
      _loading = true;
    });
    try {
      sleep(const Duration(seconds: 2));
      throw ("Debug");
    } catch (e) {
      print(e);
      setState(() {
        _loading = false;
      });
      Fluttertoast.showToast(msg: e);
    }
  }

  @override
  void dispose() {
    _emailController.dispose();
    _passwordController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {

    // I even tried this and it still fails
    // if (_loading) {
    //   return CupertinoActivityIndicator();
    // }

    return CupertinoPageScaffold(
      child: Form(
        key: _formKey,
        child: ListView(children: [
          Text('CREATE AN ACCOUNT'),
          Padding(
              padding: EdgeInsets.symmetric(horizontal: 20),
              child: MyInput(type: 'email', controller: _emailController)),
          Padding(
              padding: EdgeInsets.symmetric(horizontal: 20),
              child: MyInput(type: 'password', controller: _passwordController)),
          Padding(
            padding: EdgeInsets.only(top: 36, bottom: 14, left: 45, right: 45),

            // HERE ---- \/ \/ ----

            child: (_loading) ?
              CupertinoActivityIndicator() :
              FullButton(
                onPressed: () {
                  // I tried doing setState here but it didn't work
                  // setState(() {
                  //   _loading = true;
                  // });
                  _register(context);
                },
                text: 'CREATE AN ACCOUNT',
                fillColor: true),
            ),

          // /HERE ---- /\ /\ ----

          Center(
            child: Text(
              'FORGOT PASSWORD?',
              style: TextStyle(
                  color: Color.fromRGBO(0xEE, 0x56, 0x42, 1.0),
                  fontFamily: 'Montserrat',
                  fontSize: 12),
            ),
          ),
        ]),
      ),
    );
  }
}

如您所见，我尝试了不同的方法。我一直在网上搜索，到处都是，似乎我做的一切都是正确的。在和我有同样问题的人中，我能找到的是用于执行条件的布尔变量是在某些函数中本地声明的，或者是使用 StatelessWidgets 等的人......

我做错了什么？

Answer 1

替换

sleep(const Duration(seconds: 2));

和

Future.delayed(Duration(seconds: 2)).then((_) {
  throw ("Debug");
});

Flutter setState() 不触发重建

Flutter setState() not triggering re-build

dart

flutter

flutter-state