[iOS][Add2App]: The scroll events don't respond sometimes due to touch events

[wangying3426]

In add-to-app on iOS platform, we found an anomaly.

Steps to Reproduce

1. scroll a ListView with your finger.
2. open another native view controller during scrolling.
3. go back the ListView page.
4. try to scroll the ListView again, but it can't scroll normally.

Just like the video shown, the page cannot respond to scrolling events properly at the end of the video.

20211220-231348.mp4

[darshankawar]

@wangying3426
Can you provide flutter doctor -v and a minimal code sample or a sample github repo that we can clone and verify this ?
Thanks.

[wangying3426]

All versions have this problem, and I have fixed it, see #30422

[darshankawar]

Yes, but in order to triage this issue properly, will need a reproducible code sample.

[github-actions]

Without additional information, we are unfortunately not sure how to resolve this issue. We are therefore reluctantly going to close this bug for now.
If you find this problem please file a new issue with the same description, what happens, logs and the output of 'flutter doctor -v'. All system setups can be slightly different so it's always better to open new issues and reference the related ones.
Thanks for your contribution.

[wangying3426]

Yes, but in order to triage this issue properly, will need a reproducible code sample.

@darshankawar Here is the code sample., more information see flutter/engine#30422 please.

[darshankawar]

@wangying3426
I cloned the repo and ran it on latest master, but didn't observe any abnormal scrolling after going from Flutter to native and back. Is that a correct interpretation of the issue ?

95570.mov

Channel master, 2.9.0-1.0.pre.504