Flutter how to create List view autoscrolling?

Question

I'm trying to make a ListView that auto-scrolls to the newest data point. I tired to do this by making a _scrollToBottom function that uses the .jumpTo method.

But i get a blank screen in the app, and 'child.parentData != null': is not true. in the debug console.

Any suggestions on how i can implement auto-scrolling?

Here is the relevant portions of my current code:

ScrollController _scrollController = ScrollController();

_scrollToBottom(){  _scrollController.jumpTo(_scrollController.position.maxScrollExtent);
}

@override
  Widget build(BuildContext context) {
    return StreamBuilder(
      stream: DataShareWidget.of(context).stream,
      builder: (BuildContext context, AsyncSnapshot snapshot){
        if(snapshot.hasError){ return Text(snapshot.error);}
        if(snapshot.hasData){
          _dataFormat(snapshot.data);
          return ListView.builder(
            itemCount: _listViewData.length,
            controller: _scrollController,
            reverse: true,
            shrinkWrap: true,
            itemBuilder: (context, index) {
              _scrollToBottom();
              return ListTile(
                title: AutoSizeText(_listViewData[index], maxLines: 2),
                dense: true,
              );
            },
          );
        }
      }
    );
  }

Answer 1

What you need is to call _scrollToBottom() method once the list is built fully.

Modification is your code (without StreamBuilder):

      ScrollController _scrollController = ScrollController();
    
      _scrollToBottom() {
        _scrollController.jumpTo(_scrollController.position.maxScrollExtent);
      }
      
      @override
      void initState() {
        super.initState();
      }
    
      @override
      Widget build(BuildContext context) {
        WidgetsBinding.instance.addPostFrameCallback((_) => _scrollToBottom()); 
        return Scaffold(
          body: ListView.builder(
            itemCount: 50,
           // itemCount: _listViewData.length,
            controller: _scrollController,
            reverse: true,
            shrinkWrap: true,
            itemBuilder: (context, index) {
              return ListTile(
                title: Text('Yo Dummy Text $index'),
                // title: AutoSizeText(_listViewData[index], maxLines: 2),
                dense: true,
              );
            },
          ),
        );
      }