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flutter - 为什么使用这个简单的 initState 代码会导致 Flutter 崩溃？

问题描述

class _HomeScreenState extends State<HomeScreen> {
  String uid = "";

  @override
  void initState() {
    FirebaseAuth.instance.currentUser().then((user) {
      setState(() {
        uid = user.uid;
        super.initState();
      });
    });
  }

我运行最新版本的 Flutter，之前从未遇到过任何这些问题。Flutter 完成 xcode 构建，在模拟器上打开但只有白屏，1 秒后 Flutter 崩溃并出现以下异常：

**Failed assertion: line 1110 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not true.
#0      _AssertionError._doThrowNew (dart:core-patch/errors_patch.dart:42:39)
#1      _AssertionError._throwNew (dart:core-patch/errors_patch.dart:38:5)
#2      State.initState (package:flutter/src/widgets/framework.dart:1110:12)
#3      _HomeScreenState.initState.<anonymous closure>.<anonymous closure> (package:schoolEachother1_0/screens/home_screen.dart:25:15)
#4      State.setState (package:flutter/src/widgets/framework.dart:1233:30)
#5      _HomeScreenState.initState.<anonymous closure> (package:schoolEachother1_0/screens/home_screen.dart:23:7)
#6      _rootRunUnary (dart:async/zone.dart:1192:38)
#7      _CustomZone.runUnary (dart:async/zone.dart:1085:19)
#8      _FutureListener.handleValue (dart:async/future_impl.dart:141:18)*
#9      Future._propagateToListeners.handleValueCallback (dart:async/futu<…&gt;
*** First throw call stack:
(
    0   CoreFoundation                      0x00007fff23e3cf0e __exceptionPreprocess + 350
    1   libobjc.A.dylib                     0x00007fff50ba89b2 objc_exception_throw + 48
    2   CoreFoundation                      0x00007fff23e3cc88 +[NSException raise:format:arguments:] + 88
    3   Foundation                          0x00007fff258b8c9b -[NSAssertionHandler handleFailureInFunction:file:lineNumber:description:] + 166
    4   Runner                              0x00000001031ad6d7 _ZN8firebase9firestore4util16ObjcThrowHandlerENS1_13ExceptionTypeEPKcS4_iRKNSt3__112basic_stringIcNS5_11char_traitsIcEENS5_9allocatorIcEEEE + 343
    5   Runner                              0x00000001031acf25 _ZN8firebase9firestore4util5ThrowENS1_13ExceptionTypeEPKcS4_iRKNSt3__<…&gt;*

谁能告诉我我做错了什么？

提前致谢

标签： flutterdart

解决方案

super.initState()必须独立于initState()方法中的其余代码调用。

  @override
  void initState() {
    FirebaseAuth.instance.currentUser().then((user) {
      setState(() {
        uid = user.uid;
      });
    });
    super.initState();
  }

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