Fix: multiline textinput start "jerking" when trying to move cursor.

[xiankuncheng]

Summary

Fixes #30748: on iOS 14, when trying to hold down the space bar and move the cursor on a multi-line TextInput with lots of lines, the cursor could not be scrolled to the desired point. It works as expected on iOS 13 and before.

Figured out that iOS14 acting as expected without [setContentOffset:animated:], so exclude it when iOS version is and above 14.

Credit to @efstathiosntonas for the finding and solution provides.

Related issue

• iOS | RN 0.62.2 | The text in the Multiline TextInput starts "jerking" when moving the cursor over it with a long press on the spacebar #30748

Changelog

[iOS] [Fixed] - Fixed the issue when moving cursor in multi-line TextInput.

Test Plan

1. Launch RNTester app on iOS
2. Open TextInput in tab Components
3. Scroll to Multiline section and focus on the first child
4. Input lots of dummy texts
5. Hold the space bar (on device) or press down the mouse inside TextInput (simulator without showing keyboard)

Video Before:

RPReplay_Final1631248010.MP4

Video After:

RPReplay_Final1631248159.MP4

[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
ios	-	universal	n/a	--

Base commit: 3562364

[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
android	hermes	arm64-v8a	7,716,151	-58
android	hermes	armeabi-v7a	7,244,374	-63
android	hermes	x86	8,135,468	-66
android	hermes	x86_64	8,101,021	-60
android	jsc	arm64-v8a	9,635,411	+141
android	jsc	armeabi-v7a	8,551,154	+141
android	jsc	x86	9,649,007	+138
android	jsc	x86_64	10,258,241	+138

Base commit: 3562364

[lunaleaps]

Can we add a comment about why this is needed?

[lunaleaps]

Can we leave a comment about what this is for

[xiankuncheng]

@lunaleaps thank you for the review.
I've added some comments to explain the reason for the fix. Please let me know I could make it better 🙏

[lunaleaps]

Great thank you! I might even add a link to the issue in the comments if that's okay with you? #30748

[facebook-github-bot]

@lunaleaps has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[xiankuncheng]

@lunaleaps that makes sense, added one more comment for the link, thanks for all the help ❤️

[facebook-github-bot]

@lunaleaps has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[philIip]

great work! thanks for doing this.

[lunaleaps]

Sorry for the back and forth but chatting internally, we'll update this comment to the following since it seems like setContentOffset animated:NO was originally a fix for "flaky scrolling" for versions prior to iOS 14

// Turn off scroll animation to fix flaky scrolling.
// This is only necessary for iOS <= 13

[xiankuncheng]

No worries at all, this makes more sense and actually reduces the chance of confusion for the next maintainer, thanks for that.

[react-native-bot]

This pull request was successfully merged by @xiankuncheng in 2280187.

^{When will my fix make it into a release? | Upcoming Releases}