NSNotification NSMetadataQueryDidUpdate getting non-stop Notification messages

Question

I am implementing saving to iCloud Drive in my application. Right now I am testing the app on the simulator. I can save a file on to the iCloud Drive and it appears on the drive as expected. In my code, I have implemented NotificationCenter.default.addObserver. The startQuery() gets called with the application is made active. Here is the code sample:

@objc func startQuery()
{
    stopQuery()
    query = documentQuery()
    print( "adding notifications" )
    NotificationCenter.default.addObserver(self, selector: #selector(finishGatheringNotification(notifciations:)), name: NSNotification.Name.NSMetadataQueryDidFinishGathering, object:nil )
    NotificationCenter.default.addObserver(self, selector: #selector(didUpdateNotification(notifciations:)), name: NSNotification.Name.NSMetadataQueryDidUpdate, object:nil )
    query?.start()
}

@objc func stopQuery()
{
    guard let query = self.query else{
        return
    }
    NotificationCenter.default.removeObserver(self, name: NSNotification.Name.NSMetadataQueryDidFinishGathering, object:nil )
    NotificationCenter.default.removeObserver(self, name: NSNotification.Name.NSMetadataQueryDidUpdate, object:nil )
    query.stop()
    self.query = nil

}

     @objc func finishGatheringNotification( notifciations:NSNotification ){
        print( "called finished gathering notification" )
        processICloudFiles(notifciations: notifciations )
    }

    @objc func didUpdateNotification( notifciations:NSNotification ){
        // This seems to be getting called non-stop
        print( "called updated notification" )
        processICloudFiles(notifciations: notifciations )
    }

    @objc func processICloudFiles( notifciations:NSNotification )
    {
        guard let query = query else{
            return
        }
        query.disableUpdates()
        var metaDataItems:[NSMetadataItem] = []

        if let queryResults = query.results as? [NSMetadataItem]{
            print( "query results:\(queryResults.count)")
            for result in queryResults{
                if let fileURL = result.value(forAttribute: NSMetadataItemURLKey ) as? NSURL{
                     print( "file found in iCloud:\(String(describing: fileURL.lastPathComponent))")
                    metaDataItems.append( result )
                }
            }
            if metaDataItems.count > 0{
                updateICloudFiles(metaDataItems: metaDataItems)
            }
        }
        query.enableUpdates()
    }

However, the selector for NSMetadataQueryDidUpdate is getting called no stop. I thought it was meant to get called only when the content of the iCloud disk changes.
Any suggestions.
Thanks
Reza

Answer 1

Try to deinitialize:

deinit {
    NotificationCenter.default.removeObserver(self)
}

Answer 2

Just got a message from Apple that this is a known bug and I have posted a bug report.