react / react/react-native

maintainVisibleContentPosition incorrectly autoscrolls on ios

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Issue: Author Provided Repro Needs: Triage :mag: Platform: iOS
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描述

Description

What I want is for flatlist to maintain its position if the offset is larger than 10, otherwise automatically scroll to new content, so I am using the maintainVisibleContentPosition with values of { minIndexForVisible: 0, autoscrollToTopThreshold: 10, }. Now this works correctly on android but not on ios.

Here is a small reproducible or its snack:

import React, {useState} from 'react';
import {
  SafeAreaView,
  View,
  FlatList,
  StyleSheet,
  Text,
  StatusBar,
  Button,
} from 'react-native';

type ItemProps = {title: string};

const Item = ({title}: ItemProps) => (
  <View style={styles.item}>
    <Text style={styles.title}>{title}</Text>
  </View>
);

const App = () => {
  const [data, setData] = useState([1, 2, 3, 4, 5, 6, 7, 8, 9]);

  const addToTop = () => {
    setData([data[0] - 1, ...data]);
  };

  const removeFromTop = () => {
    const [_, ...rest] = data;
    setData(rest);
  };

  return (
    <SafeAreaView style={styles.container}>
      <FlatList
        maintainVisibleContentPosition={{ minIndexForVisible: 0, autoscrollToTopThreshold: 10, }}
        data={data}
        renderItem={({item}) => <Item title={`Item ${item}`} />}
        keyExtractor={item => item.toString()}
      />
      <Button title="add to top" onPress={addToTop} />
      <Button title="remove from top" onPress={removeFromTop} />
    </SafeAreaView>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    marginTop: StatusBar.currentHeight || 0,
  },
  item: {
    backgroundColor: '#f9c2ff',
    padding: 20,
    marginVertical: 8,
    marginHorizontal: 16,
    height: 480,
  },
  title: {
    fontSize: 32,
  },
});

export default App;
Steps to reproduce
  1. Copy the repro above to some rn project
  2. Scroll to half of the first element, then press addToTop, on android position will be maintained which is correct but on ios it autoscrolls.
React Native Version

0.73.4

Affected Platforms

Runtime - iOS

Output of npx react-native info
System:
  OS: macOS 14.1.2
  CPU: (16) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
  Memory: 2.57 GB / 16.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 18.17.1
    path: ~/.nvm/versions/node/v18.17.1/bin/node
  Yarn:
    version: 1.22.19
    path: ~/.nvm/versions/node/v18.17.1/bin/yarn
  npm:
    version: 9.6.7
    path: ~/.nvm/versions/node/v18.17.1/bin/npm
  Watchman:
    version: 2024.01.22.00
    path: /usr/local/bin/watchman
Managers:
  CocoaPods:
    version: 1.15.0
    path: /Users/ramiel/.rbenv/shims/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 23.2
      - iOS 17.2
      - macOS 14.2
      - tvOS 17.2
      - visionOS 1.0
      - watchOS 10.2
  Android SDK: Not Found
IDEs:
  Android Studio: 2023.1 AI-231.9392.1.2311.11076708
  Xcode:
    version: 15.2/15C500b
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 11.0.15
    path: /usr/local/opt/openjdk@11/bin/javac
  Ruby:
    version: 2.7.6
    path: /Users/ramiel/.rbenv/shims/ruby
npmPackages:
  "@react-native-community/cli": Not Found
  react:
    installed: 18.2.0
    wanted: 18.2.0
  react-native:
    installed: 0.73.4
    wanted: 0.73.4
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: false
iOS:
  hermesEnabled: true
  newArchEnabled: false


### Stacktrace or Logs

```text
No Stacktrace or Logs
Reproducer

https://snack.expo.dev/@ramiel99/spunky-green-peanut

Screenshots and Videos

https://github.com/facebook/react-native/assets/80689446/456e98f1-d5a8-4253-9a53-9b8d08e61426

贡献指南

打开贡献指南

从这里开始

  1. 先读完整个 Issue,再读项目的贡献指南。
  2. 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
  3. Fork 仓库,在一个分支上完成修改。
  4. 提交 Pull Request,并在描述里引用这个 Issue 编号。

调研方向

首先在 iOS 和 Android 上运行链接的 Snack,并使用 add-to-top 和 remove-from-top 操作测试 FlatList 的 maintainVisibleContentPosition。跟踪 FlatList 在报告的阈值附近的行为,然后验证 iOS 在 offset 大于 10 时会保持该 offset,只有在其处于阈值范围内时才会自动滚动,与 Android 的行为一致。

由索引模型根据 Issue 内容生成。

评估

技术栈
ios, react-native
领域
mobile
Issue 类型
缺陷
难度
4/5
预计耗时
3-5 天
活跃度
停滞
描述清晰度
基本清楚
新手友好度
42/100

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