Issue when changing multiple keys in macOS Monterey

[paxos]

First off: Thank you for this library. This is exactly what I was looking for.

There seems to be a sync issue with macOS Monterey (tested version: 12.0.1 (21A558))

It seems that Apple changed the behavior on how it posts the NSUbiquitousKeyValueStore.didChangeExternallyNotification notification.

Formerly, notification.userInfo?[NSUbiquitousKeyValueStoreChangedKeysKey] contained ALL changed keys (including ZephyrSyncKey). In my tests, this is no longer the case. Instead, the notification gets posted multiple times, with different values. Here is what happens in my scenario:

We have Client A and Client B. Lets say A changes 2 keys. What happens is:

Zephyr:

• Receives NSUbiquitousKeyValueStore.didChangeExternallyNotification notification for key 1, stores remote value to local user defaults.
• Zeyphr sets local sync date
• Receives NSUbiquitousKeyValueStore.didChangeExternallyNotification notification for key 2, throws it away, because local sync date is newer
• Receives NSUbiquitousKeyValueStore.didChangeExternallyNotification notification for key ZephyrSyncKey

Zephyr/Sources/Zephyr.swift

Lines 456 to 459 in d86fe8c

	if let localStoredDate = zephyrLocalStoreDictionary[ZephyrSyncKey] as? Date,
	!(remoteStoredDate.timeIntervalSince1970 > localStoredDate.timeIntervalSince1970) {
	return
	}

In this scenario, the second value was thrown out and both apps are no longer in sync.

I can't tell if this is a (beta) bug or if this is the new, expected behavior. I can't think of a good way to fix this, as we would now need to store the sync date of each property - or somehow batch all those updates coming in.

[ArtSabintsev]

Thanks for the callout.

If this is in a beta build, I'd wait it out. I don't know how to fix it either. If this turns out to be a massive problem then I'll spend some time thinking on it.

Let me know what you see in newer betas.

[paxos]

Forgot to mention: I also filled a radar. I can put it on Open Radar as well.

[ArtSabintsev]

That sounds like a great idea!

[ArtSabintsev]

Closing for now - please reopen if you still see this issue.

[paxos]

Issue is still existent on Monterey 12.0.1 as well as 12.1 Beta 1.

I would recommend reopening this. The library does not work in this form on Monterey unfortunately :-/

[paxos]

I confirmed that keysDidChangeOnCloud gets called with ALL changed keys on < Monterey, but multiple times with only 1 key on Monterey.

[ArtSabintsev]

Mind opening a new ticket? I'm ooto for a few more days. Will take it from there.

Most likely will stop support macOS since I don't have time to really address this issue.

Arthur