You cannot schedule operations at specific times in iOS (except for a local notification, which, as you said, does not match what you need).
You can use the background fetch mode to periodically let your application check for new data. You can set the interval (although this is only a guideline for iOS, not a strict schedule) how often your application wakes up.
iOS performFetchWithCompletionHandler, , . , UIBackgroundFetchResultNoData. , , UIBackgroundFetchResultNewData