iOS: Narrow sometimes lands very far in the past.

[chrisbobbe]

This seems to be happening again on iOS: the initial scroll position (or maybe the scroll position a fraction of a second after opening a narrow) is far higher than it should be. It's not yet clear how this relates to #3457 or #4863, and I don't yet have a clear reproduction recipe.

For anyone wishing to help, a great first step would be to find a good reproduction recipe: a list of steps that I or anyone else can take to see the bug happening. So far it only seems to happen sometimes, and I haven't found a pattern.

@gnprice said, in #3457 (comment):

There's still a potential opportunity here to simplify our interactions with the browser's layout and scrolling: #3457 (comment) That could potentially make us more robust to having an issue like this appear in the future. If we see another issue like this one in the future, that's one direction we'll want to investigate.

So let's look into that too. I think I'd actually like to take a slightly different approach. The proposal I made there wasn't ideal: it would change getFirstUnreadIdInNarrow so that the ID it returns isn't always…the first unread ID in the narrow. That function is right to return null when "the first unread ID in the narrow" can't be given because it doesn't exist. But after calling that function, we can conditionalize on a null value so that we still use the last message ID for initialScrollMessageId.

[thisisnitish]

@chrisbobbe!, I've a question, since I use Android device in real so I can't experience iOS in real. But can this issue be done using iOS simulator?(May be the question doesn't make sense) 🙂.
Also, because the issue I'm facing right now with RN version which changing ios/Podfile.lock, can I start working on this issue?.
Thanks 🙂

[chrisbobbe]

This issue only really makes sense to work on if you have an iOS device or you can run an iOS simulator.

To run the simulator, you'll need Xcode, which means you'll need an Apple computer: https://github.com/zulip/zulip-mobile/blob/main/docs/howto/ios-tips.md#running-on-ios-simulator. Do you have one of those?

[thisisnitish]

yeah @chrisbobbe!, I do have a Mac this is why I'm asking if it can be done in iOS simulator 😅 and I do have Xcode?

[chrisbobbe]

Sure, I'd be very interested in a consistent reproduction recipe in an iOS simulator! 🙂 The key thing to look for is a list of steps that other people (not just you in your unique environment) can follow to see the bug themselves, every time, as many times as they need to debug further.

[thisisnitish]

sure @chrisbobbe!, let me thoroughly go through the issue once and then I'll get back to you.

[thisisnitish]

Thanks for your patience @chrisbobbe!, I've gone through it. So far I observed is:

• When I click any topic, stream I see narrow goes so much above and when I click any PM then I see sometimes and sometimes not.
• Basically, I've observed is, the number of times narrow lands very far in past for topics, streams >> the number of times narrow lands very far in past for PMs.
  I haven't found any pattern yet.
  Thanks.

[thisisnitish]

@chrisbobbe!, I tried a lot but couldn't find anything. I will try this issue after sometime. Meanwhile I'll take some other issue. Thanks 🙂