Animated GIFs don't animate in lightbox, on iOS

[eugenolman]

Full page animated gifs do now show animated (in lightbox). In a thread they are animated.
Happens in IOS app (tested on miniIpad IOS 12)

In Android App, animations show in threads and in full screen. The same in webapp in Chrome.

Note; I am not a coder, this is my first issue on github / Zulip ever. If I did something wrong or can do better please let me know.

[gnprice]

Hmm! Thanks for the report. I reproduce the issue, with the current beta version v26.28.151.

We previously had #3497 and fixed that with #3825 -- but that was specific to Android and it seems we didn't notice there was also a problem on iOS.

[gnprice]

The earlier fix #3825 added something that the React Native docs specifically say is needed on Android:
https://reactnative.dev/docs/0.59/image#gif-and-webp-support-on-android

The docs don't say anything about animated-GIF support being missing on iOS. So the first thing we'll need to do to resolve this is some debugging -- why are animated GIFs not working?

A quick reproduction is to go to #test here > gif test on chat.zulip.org. (Same topic @agrawal-d used in the demonstration in #3825.)