The getData call for RTDB completion handler is not called on the main thread

[puf]

[REQUIRED] Step 1: Describe your environment

• Xcode version: _____
• Firebase SDK version: _____
• Installation method: CocoaPods | Carthage | Zip file | Swift Package Manager (select one)
• Firebase Component: Realtime Database

[REQUIRED] Step 2: Describe the problem

See https://stackoverflow.com/q/67941742 for the original report.

Steps to reproduce:

While the Firebase SDK performs its network and other I/O on a background thread, it actually calls your callback on the main thread.

But it seems that getData does not do that here. See below for relevant code. 👇

Relevant Code:

This works

databaseReference.observe(.value) { [weak self] snapshot in
        guard let self = self else { return }
        self.tableView.reloadData()
}

This throws an error UICollectionView.reloadData() must used from main thread only:
databaseReference.getData { [weak self] error, snapshot in
guard let self = self else { return }
self.tableView.reloadData()
}

[google-oss-bot]

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[paulb777]

Fixed by #8247 and merged for 8.5.0 release