Why is NSMetadataQueryDidUpdateNotification being called several times in quick succession?
问题 In order to monitor file changes in my iCloud container, I've registered for [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(processiCloudUpdates:) name:NSMetadataQueryDidUpdateNotification object:nil]; Ideally, whenever I receive the message that updates have been made, I'd like to open each of my UIDocs and check if settings have been changed. This would be fine, if NSMetadataQueryDidUpdateNotification was only called once. However, it is being fired several times