Flutter在sliver列表上每x次添加一项

import 'package:flutter/material.dart';

class MySliverList extends StatefulWidget {
  @override
  _MySliverListState createState() => _MySliverListState();
}

class _MySliverListState extends State<MySliverList> {
  List<String> items = ['Item 1', 'Item 2', 'Item 3'];
  int counter = 0;

  @override
  Widget build(BuildContext context) {
    return CustomScrollView(
      slivers: <Widget>[
        SliverAppBar(
          title: Text('Sliver List'),
          floating: true,
        ),
        SliverList(
          delegate: SliverChildBuilderDelegate(
            (BuildContext context, int index) {
              if ((index + 1) % x == 0) {
                // 添加新的列表项
                return ListTile(
                  title: Text('New Item ${counter + 1}'),
                );
              } else {
                // 显示原有的列表项
                int itemIndex = index - (index ~/ x);
                return ListTile(
                  title: Text(items[itemIndex]),
                );
              }
            },
            childCount: items.length + (counter ~/ x),
          ),
        ),
      ],
    );
  }
}