传递 scrollController 时 CustomScrollView 滚动行为会发生变化

如何解决传递 scrollController 时 CustomScrollView 滚动行为会发生变化

我正在尝试自动滚动到 SliverList 内的 CustomScrollView 的末尾。 SliverList 本身没有控制器属性，因此我必须将 ScrollController 传递给 CustomScrollView。

问题是当我将控制器传递给 CustomScrollView 时，它的行为会发生变化，它不再滚动外部列表，也不会导致 SliverAppBar 小部件折叠。如何自动滚动 SliverList 并像以前一样保持 CustomScrollView 的行为？

这是我的代码：

class _MyHomePageState extends State<MyHomePage> {
  ScrollController _scrollController = ScrollController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text(widget.title),),floatingActionButton: FloatingActionButton(
          onPressed: () {
            _scrollController.animateTo(
              _scrollController.position.maxScrollExtent,curve: Curves.easeOut,duration: const Duration(seconds: 1),);
          },body: NestedScrollView(
          headerSliverBuilder: (BuildContext context,bool innerBoxIsScrolled) {
            return <Widget>[
              SliverAppBar(
                expandedHeight: 230.0,pinned: true,flexibleSpace: FlexibleSpaceBar(
                  title: Text('SliverAppBar Expand'),)
            ];
          },body: CustomScrollView(
                //When controller is passed to CustomScrollView,its behavior changes
                // controller: _scrollController,slivers: [
                  //Some widgets are here
                  SliverList(
                    delegate: SliverChildBuilderDelegate(
                      (context,index) {
                        return Container(
                          height: 80,color: Colors.primaries[index % Colors.primaries.length],alignment: Alignment.center,child: Text(
                            'Item : $index',);
                      },childCount: 20,],);
      }
    }

解决方法

我想您可能会注意到此处示例的解释：NestedScrollView class

// The "controller" and "primary" members should be left
// unset,so that the NestedScrollView can control this
// inner scroll view.
// If the "controller" property is set,then this scroll
// view will not be associated with the NestedScrollView.
// The PageStorageKey should be unique to this ScrollView;
// it allows the list to remember its scroll position when
// the tab view is not on the screen.

和

// This Builder is needed to provide a BuildContext that is
// "inside" the NestedScrollView,so that
// sliverOverlapAbsorberHandleFor() can find the
// NestedScrollView.

正确的方法是获取CustomScrollView使用的控制器，而不是添加一个新的控制器。

可以通过在 CustomScrollView 上方添加一个 Builder 并将控制器分配给 _scrollController 来完成。

...
  body: NestedScrollView(
    ...
    body: Builder(
      builder: (context){
        _scrollController = PrimaryScrollController.of(context);
        return CustomScrollView(
          ...
      },),...