Reverts "Timing: Fixes timer when app get into background (#24649)"

[radko93]

This reverts commit 3382984

Summary

This is related #26696 - an issue where the app would be closed immediately after going to background on iOS 13.1/13.2 and was investigated by @minhtc #26696 (comment). The commit that is being reverted is apparently causing the app to be closed immediately. This has to be reverted in master separately as the file differs there.

Changelog

[iOS] [Fixed] - Reverts commit causing a crash in the background

Test Plan

Create an empty app on 0.61.x with a timer, put it in the background.

[zhongwuzw]

@radko93 Hey, seems iOS13 killed background apps much more aggressively, because we just use UIApplication background task, is this means we can't use it anymore? If we create a new iOS project(not integrate RN), just use UIApplication background task, is it also crashed?

[radko93]

@zhongwuzw I think iOS 13.1 put some stricter limits on how this works. https://forums.developer.apple.com/thread/85066:

Failing to end a background task is the #1 cause of background task problems on iOS. This usually involves some easy-to-overlook error in bookkeeping that results in the app beginning a background task and not ending it.

Maybe we don't stop the background task in time, I'm not sure at this time, but we should investigate later on. You can try to experiment with iOS 13.1.

[ex3ndr]

Woah, starting background task and never stop it? Of course iOS will kill your app otherwise. It was the same logic like forever.

[radko93]

@cpojer please look here and at #27073

[zhongwuzw]

Woah, starting background task and never stop it? Of course iOS will kill your app otherwise. It was the same logic like forever.

@ex3ndr You can check the commit to see wether we stop it :).

[zhongwuzw]

@zhongwuzw I think iOS 13.1 put some stricter limits on how this works. https://forums.developer.apple.com/thread/85066:

Failing to end a background task is the #1 cause of background task problems on iOS. This usually involves some easy-to-overlook error in bookkeeping that results in the app beginning a background task and not ending it.

Maybe we don't stop the background task in time, I'm not sure at this time, but we should investigate later on. You can try to experiment with iOS 13.1.

🤔 I don't have iOS13.0 or 13.1 now :), is this not a crash, right? it terminated by system after seconds, and I think we stop the background task in time, we can have two options to fix this:

1. Just revert it, disable the background timer feature for all iOS system users.
2. Provide an option for Timer module, developer can choose wether to enable/disable the background timer on different iOS version.

@radko93 What do you think?

[radko93]

@zhongwuzw we should make the users safe now, then we can bring this back improved.

[grabbou]

FYI let's keep the discussion under #27073 - that's the PR against master and will be easier to manage for other maintainers.

Meanwhile, I think it's fair to revert something that causes a major regression. We can always re-iterate again.