动画失败断言颤动

Question

这个断言现在跟着我因为某种原因使用不同的代码，搜索它，发现flutter团队现在还没有解决它，我们有什么可以做的吗？

v`I/flutter ( 5598): Another exception was thrown: 
'package:flutter/src/animation/animations.dart': Failed assertion: line 
376 pos 15: 'parent != null': is not true.
I/chatty  ( 5598): uid=10085(com.example.gam3ity_aa) 1.ui identical 21 
lines
I/flutter ( 5598): Another exception was thrown: 
'package:flutter/src/animation/animations.dart': Failed assertion: line 
376 pos 15: 'parent != null': is not true.
I/flutter ( 5598): Another exception was thrown: 
'package:flutter/src/animation/animations.dart': Failed assertion: line 
376 pos 15: 'parent != null': is not true.
I/chatty  ( 5598): uid=10085(com.example.gam3ity_aa) 1.ui identical 10 
lines
I/flutter ( 5598): Another exception was thrown: 
'package:flutter/src/animation/animations.dart': Failed assertion: line 
376 pos 15: 'parent != null': is not true.
I/flutter ( 5598): Another exception was thrown: 
'package:flutter/src/animation/animations.dart': Failed assertion: line 
376 pos 15: 'parent != null': is not true.
I/chatty  ( 5598): uid=10085(com.example.gam3ity_aa) 1.ui identical 8 
lines
I/flutter ( 5598): Another exception was thrown: 
'package:flutter/src/animation/animations.dart': Failed assertion: line 
376 
 pos 15: 'parent != null': is not true.

`

Answer 1

当我意外地使用 (parent: null) 创建 Tween 对象时，就会发生这种情况

  @override
  void initState() {
    _animation = Tween(begin: 0.0, end: 1.0).animate(CurvedAnimation(
      parent: null, // <---------------- This line should be an AnimationController
      curve: widget.curve,
      reverseCurve: widget.reverseCurve ?? widget.curve,
    ));
    super.initState();
  }

本来应该是这样的：

  AnimationController _animationController;
  Animation _animation;

  @override
  void initState() {
    _animationController = AnimationController(
        duration: Duration(milliseconds: 500),
        reverseDuration: Duration(milliseconds: 1000),
        vsync: this,
        value: 1.0
    );
    _animation = Tween(begin: 0.0, end: 1.0).animate(CurvedAnimation(
      parent: _animationController,
      curve: widget.curve,
      reverseCurve: widget.reverseCurve ?? widget.curve,
    ));
    super.initState();
  }