iOS only: `onChangeText` of `TextInput` is fired with text longer than `maxLength`

Description

We noticed that sometimes the onChangeText event of TextInput was fired with text longer than maxLength. According to the doc, this behaviour seems to be unexpected.

maxLength:
Limits the maximum number of characters that can be entered.

This happens only on iOS relating to autocompletion.

Steps to reproduce

Here is a snack link to reproduce the issue: https://snack.expo.dev/@yupeng_li/textinput

It contains only a TextInput component and maxLength is set to 3. If you type in bef and let the autocomplete suggestion come up, you will see an alert triggered by onChangeText when text is longer the maxLength.

In the screenshot below, the text returned is "Before", and the text displayed in the input is "ore".

React Native Version

0.71.14

Affected Platforms

Runtime - iOS

Output of npx react-native info

info Fetching system and libraries information...
System:
    OS: macOS 14.1.2
    CPU: (10) arm64 Apple M1 Pro
    Memory: 81.80 MB / 32.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 18.17.0 - ~/Library/Caches/fnm_multishells/24849_1670237417415/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 9.6.7 - ~/Library/Caches/fnm_multishells/24849_1670237417415/bin/npm
    Watchman: 2023.10.09.00 - /opt/homebrew/bin/watchman
  Managers:
    CocoaPods: Not Found
  SDKs:
    iOS SDK:
      Platforms: DriverKit 23.0, iOS 17.0, macOS 14.0, tvOS 17.0, watchOS 10.0
    Android SDK: Not Found
  IDEs:
    Android Studio: 2022.3 AI-223.8836.35.2231.10671973
    Xcode: 15.0.1/15A507 - /usr/bin/xcodebuild
  Languages:
    Java: 11.0.19 - /Users/yupeng/.sdkman/candidates/java/11.0.19-tem/bin/javac
  npmPackages:
    @react-native-community/cli: Not Found
    react: 18.2.0 => 18.2.0
    react-native: 0.71.14 => 0.71.14
    react-native-macos: Not Found
  npmGlobalPackages:
    *react-native*: Not Found
info React Native v0.73.0 is now available (your project is running on v0.71.14).
info Changelog: https://github.com/facebook/react-native/releases/tag/v0.73.0
info Diff: https://react-native-community.github.io/upgrade-helper/?from=0.71.14
info For more info, check out "https://reactnative.dev/docs/upgrading".

Stacktrace or Logs

No stacktrace

Reproducer

https://snack.expo.dev/@yupeng_li/textinput

Screenshots and Videos

No response

リンクされた Snack reproducer と、iOS における TextInput onChangeText/maxLength の動作から始めます。特に autocomplete がテキストを挿入する場合を確認してください。iOS TextInput のエントリーポイントを追跡し、フィールドには「ore」と表示されているのに callback が「Before」を受け取る理由を特定します。autocomplete によって onChangeText が maxLength より長いテキストを報告できなくなり、reproducer の動作が修正されれば完了です。