Cwa-app-ios: Glitch in scrolling the main screen

[ndegendogo]

Avoid duplicates

• [x] Bug is not mentioned in the FAQ
• [x] Bug is not already reported in another issue

Describe the bug

In a specific scenario, the main screen jumps during scrolling. See details below.

Expected behaviour

Smooth scrolling

Steps to reproduce the issue

Reproduce as follows:

start cwa and see the main screen

scroll down to the very bottom.

select "App Informationen", then back to the main screen

now scroll slowly up again.
Expected: smooth scrolling
Observed: during scrolling, the screen suddenly jumps up a bit

Technical details

• cwa v 1.1.2 (0)
• iOS Version: 13.6
• Device: iPhone 8

Possible Fix

Additional context

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Internal Tracking ID: EXPOSUREAPP-2007 obsolete
Internal Tracking ID: EXPOSUREAPP-4732 in progress
PR https://github.com/corona-warn-app/cwa-app-ios/pull/1890

[Ein-Tim]

I've tested this on my iPhone XR, there everything is normal. On an iPhone 6s, the glitch occurs.
Could it be that this only happens on smaller screen iPhones?

[ndegendogo]

Could it be that this only happens on smaller screen iPhones?

yes, definitely. I think the root cause could be some hard-coded numbers / dimensions in the layout that don't match the smaller screens. And luckily it is reproducible on the simulator.

[GPclips-zz]

Hello @ndegendogo and @Ein-Tim ,

thanks for reporting this issue. I will share it with our developemnt team to work on it as soon as possible.

Thank you,
LMM

Corona-Warn-App Open Source Team

[ndegendogo]

I have now found a different scenario with similar effect, it seems related.

cwa v 1.1.2(0) / iOS 13.6 / iPhone 8

Scenario:

• start cwa
• scroll to the very top
• exit cwa (home button) and start cwa again
• see the very top of the screen as expected
• now scroll to the very bottom
• exit cwa (home button) and start cwa again
  Expected: see the very bottom of screen
  Observed: visible part of screen is offset from the bottom

And now comes the interesting part:

• scroll again to the very bottom
• exit cwa (home button) and start cwa again
• now you see indeed the very bottom of screen as expected

[JoachimFritsch]

Dear all,
are these behaviors still reproducible with V1.5.0? On my device (iPhone 7) I can reproduce any of the above mentioned behavior.

[ndegendogo]

@JoachimFritsch you can reproduce with cwa 1.5.0 or you can not? 🤪

We already suspect that it may be related to devices with smaller screen height (like iPhone 8).

I still get those glitched with cwa 1.5.
I'll test and report in more detail later.

[ndegendogo]

Tested again with configuration: cwa 1.5.0(8) / iOS 14.1 / iPhone 8.

I could reproduce this scenario exactly as described above.

The original described scenario, however, does no longer jump, but behaves now as follows:

• start cwa and see the main screen
• scroll down to the very bottom.
• select "App Informationen", then back to the main screen
  You see a visible offset from the bottom.
• Scroll slowly up again.
  Observed: smooth scrolling, as it should be.

So, although not perfect, but the visible effect is negligible.

[Ein-Tim]

Can confirm @ndegendogo's founds

[Ein-Tim]

Issue is still here in 1.6.0/1.6.1. Any updates @JoachimFritsch?

[dsarkar]

@ndegendogo, @Ein-Tim, issue still present in CWA version 1.7.1. We will update the developers. Best wishes, DS

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Corona-Warn-App Open Source Team

[ndegendogo]

@dsarkar off-topic:
could you please have a look at this android ticket?
Seems your robot forgot to pick it up ...

[Ein-Tim]

Still reproducible with 1.9.1. Only on small screen iPhones.

BTW: You could add the UX label here

[dsarkar]

Hi @Ein-Tim, thanks. Info was forwarded to the developer's ticket. Best, DS

[Ein-Tim]

This is still reproducible with 1.10.1.

There is also a new behavior (which also affects large screen iPhones):

1. Scroll all the way down to the bottom
2. Click on the contact diary box
3. Leave the contact diary box
4. See a visible offset from the bottom

First time you do this is the most noticeable offset, second time only a small one and third time everything is normal.

Screenrecordings.zip

[dsarkar]

Hi @Ein-Tim, thanks. Info was forwarded to the developer's ticket.

Best wishes,
DS

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Corona-Warn-App Open Source Team

[Ein-Tim]

I can't reproduce this anymore under version 1.11.

Edit:
There is a new, even worse behavior with version 1.11.:

https://user-images.githubusercontent.com/67682506/106241723-cdfa7080-6206-11eb-9ec3-357aec3858fa.MOV

https://user-images.githubusercontent.com/67682506/106241752-db175f80-6206-11eb-94a4-cb51fea2697b.MOV

If you scroll from the bottom to the top you will see that the view jumps from the contact diary box directly to the top. This is only visible if you scroll slow. But also, when you scroll a bit faster (not too fast) you can see this glitch:

https://user-images.githubusercontent.com/67682506/106242338-cdaea500-6207-11eb-914b-60d65926f21b.mp4

The whole behavior of the home screen is a bit, I would say, strange... I propose that you test everything internal on large and small screen iPhones and then fix it 😀

[dsarkar]

@Ein-Tim Yes, I can reproduce your first vid on the iPhone 6s

[dsarkar]

@Ein-Tim all iOS 14.4 ?

[Ein-Tim]

@dsarkar
Yes

[dsarkar]

ok, thanks, updated internal ticket.

[ndegendogo]

@dsarkar the simulator that Apple provides for iPhone app development has a slow-motion mode, where you can watch more closely if an animation is smooth; and you can configure the simulator for different device types ( = screen sizes).

Of course, this does not tell you about the root cause of a broken animation; but is still very useful to verify if a fix has the desired effect.

[dsarkar]

• Internal Tracking ID: EXPOSUREAPP-2007 obsolete now
• Internal Tracking ID: EXPOSUREAPP-4732 new ticket in progress
• Fix planned for 1.12

[ndegendogo]

Another observation, possibly related: the scrollbar of the main screen jumps. Especially when scrolling upwards.

cwa 1.11.0(9) / iOS 14.2 / iPhone 8

[dsarkar]

@ndegendogo Good Morning, your observation is forwarded to the devs. Thanks.

[Ein-Tim]

PR fixing this: #1890

[ndegendogo]

@Ein-Tim @nickguendling wow - thanks!

[ndegendogo]

Just tested it with simulator for iPhone 8 on the release/1.12.x branch.
Very smooth now, exactly as it should be.
Many thanks!

From my side I regard this as fixed.
@Ein-Tim, I assume you would also like to test it?

[Ein-Tim]

@ndegendogo

I would suggest to leave this open until 1.12 is released (10.02.) so that I can test this too (I'm sadly not (yet) able to test it via the simulator).

Thanks for asking @ndegendogo ❤️

[dsarkar]

@ndegendogo Thanks for the feedback. UPDATE: actually forwarded your testing result and thanks to the devs.

[Ein-Tim]

1.12.1 has been released (https://github.com/corona-warn-app/cwa-app-ios/releases/tag/v1.12.1) and I can confirm that this has been fixed. So feel free to close this @ndegendogo, and thanks for waiting until I was able to confirm this!

[dsarkar]

Dear @ndegendogo and community.

Thanks again for all the contributions. Best wishes, DS

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Corona-Warn-App Open Source Team