[bug][ios]: using getItemType causes blanks and overlapping items

[hirbod]

Current behavior

Using getItemType causes blanks and overlapping items.

I reproduced a bug where using getItemType causes blanks and overlapping items. This does only happen when using different types but the elements having the same height. In my Expo Snack, just using two types (e.g "header" and "row" does not break), since header and row have different heights. But I used different types (in my real app) because the items have different icons and styling, so I tried to add more types in order to optimize renders. While I could just use two types to "fix" this issue, getItemType should never cause this blanks, even when the items have the same height.

RPReplay_Final1663187328.mp4

I was only able to reproduce this on iOS, but honestly haven't tried android enough. It is not breaking on web.

Expected behavior

Should not cause blanks and overlapping items

To Reproduce

https://snack.expo.dev/@hirbod/getitemtype-failing

Platform:

• iOS
• Android

Environment

Happens on iOS (bare react-native and expo, 1.1.0 and 1.2.1)

[naqvitalha]

@hirbod I looked into this and it seems like getItemType is returning a random value in the sample. Are you able to reproduce if you don't return something random?

[hirbod]

@naqvitalha yes, I am able to reproduce this. The random value was only for demonstration. It also happens when I just have 2 different types. (like in my app)

It does not happen when both types have different dimensions, only when you have different types with same item dimensions - at least thats my guess.

[hirbod]

@naqvitalha we had reports in the Discord group that this issue can even randomly occur even without the use of getItemType. So it just might be a coincidence or there is a general issue that can happen

[BalogunofAfrica]

Hi @hirbod what did you do to fix this? Currently experiencing this in our app

[hirbod]

For me the only fix was to omit getItemType

[chrisnojima]

Hey,
I'm working through similar issues and have a workaround that I'm working on here: https://github.com/keybase/client/pull/25431/files#diff-f67a7205112c41c7aafa06a4bcd839cb2918b1c922d5297fab63a0a4b84a224b maybe it'll be useful and maybe it could be applied upstream

[naqvitalha]

I think we have finally figured this out. More updates soon. This was a tough one.

[singhayush1403]

Is this fixed? Still happening with me on version 1.6.1