react / react/react-native

Scroll position not maintained after resume on iOS

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#54,979 5 comments 2 reactions 0 assignees View on GitHub

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Needs: Triage :mag: Platform: iOS
Dominant language
C++
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Description

Description

The scroll position of a ScrollView that has been scrolled to the bottom is not maintained on resume after being backgrounded on iOS.

The position appears to be reset to landscape when the device is in portrait. In addition to triggering an unexpected scroll, the layoutMeasurement.height of the scroll event indicate that the device orientation has changed to portrait. However, no corresponding onLayout event is triggered, and the app resumes in landscape.

Initially I thought this was an issue with FlashList but I found that it can be reproduced with ScrollView alone.

Steps to reproduce
  1. Run the Snack on an iPad simulator
  2. Rotate the screen to landscape (app must be fullscreen)
  3. Scroll to the bottom
  4. Background the app
  5. Wait a few seconds
  6. Open the app
  7. See that the ScrollView position has changed
React Native Version

0.83.1

Affected Platforms

Runtime - iOS

Output of npx @react-native-community/cli info
System:
  OS: Linux 6.17 Debian GNU/Linux 13 (trixie) 13 (trixie)
  CPU: (8) x64 Intel(R) Core(TM) i7-8550U CPU @ 1.80GHz
  Memory: 11.53 GB / 23.24 GB
  Shell:
    version: "5.9"
    path: /usr/bin/zsh
Binaries:
  Node:
    version: 22.21.0
    path: /usr/bin/node
  Yarn:
    version: 1.22.22
    path: /usr/bin/yarn
  npm:
    version: 10.9.4
    path: /usr/bin/npm
  Watchman: Not Found
SDKs:
  Android SDK: Not Found
IDEs:
  Android Studio: AI-252.27397.103.2522.14514259
Languages:
  Java: Not Found
  Ruby:
    version: 3.0.2
    path: /home/mhoran/.rbenv/shims/ruby
npmPackages:
  "@react-native-community/cli": Not Found
  react:
    installed: 19.1.0
    wanted: 19.1.0
  react-native:
    installed: 0.81.5
    wanted: 0.81.5
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: Not found
  newArchEnabled: Not found
iOS:
  hermesEnabled: Not found
  newArchEnabled: Not found
Stacktrace or Logs

https://github.com/user-attachments/assets/6cc7ab12-6996-4576-86d3-d9f696875386

MANDATORY Reproducer

https://snack.expo.dev/@mhoran/restless-green-graham-crackers

Screenshots and Videos

No response

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by running the mandatory Snack reproducer on an iPad simulator and follow the listed rotation, scroll, background, and resume steps. Compare the ScrollView scroll event's layoutMeasurement.height with the device orientation and check whether an onLayout event occurs during resume. Done means the scroll position remains stable and orientation/layout state is consistent after reopening the app.

Written by the indexing model from the issue text.

Assessment

Tech stack
react-native
Domain
mobile
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
48/100

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