Is it possible to dynamically set UUID on iBeacon app? - core-location

Question

I have a beacon device that broadcasts different UUID values based on a custom rotation scheme.
Usually, the developer has to set static UUID to be recognized by the app like that (example for iOS):
CLBeaconRegion *region = [[CLBeaconRegion alloc] initWithProximityUUID:uuid major:major minor:minor identifier:identifier];
I was wondering if there is a way to dynamically generate (or receive from a server) the UUIDs to be recognized.
Having said that I am still having difficulties understanding the internal mechanisms of how beacons are understood by iOS and Android. From my understanding, the BLE module of the phone forwards all well-formated iBeacons to the OS which maintains a list of recognized UUIDs. After a simple look-up and if a match is found the OS will bring the corresponding app to the foreground.
However, when does the app's recognized UUID(s) get registered with the OS? How often do they get re-registered? I would be grateful if anyone would point me to any relevant online material or at least the mention the mechanisms involved in this process.

Answer 1

On both Android and iOS registering for beacon ProximityUUIDs to detect amounts to nothing more than applying a filter on Bluetooth packets that match the byte pattern of the beacon and ProximityUUID. The important difference is that on iOS the operating system framework that does the filtering, CoreLocation, puts severe limits on the filters you can have. The iOS limits include:
You can have only 20 UUIDs monitored at any given time for a single app.
A device-wide limit of the first 30 UUIDs monitored gets hardware assisted fast detection. Later UUIDs to register get slower (several minute delays in the background) detections.
You cannot monitor or range for any UUID (global wildcard)
You can, however, change the 20 UUIDs you app is monitoring at any time -- even once every few seconds. The trick is that your app must be in the foreground to do this, or have a permitted way to run in the background to do this UUID rotation.
To register a UUID for monitoring on iOS, you simply declare a region with that UUID ( typically without specifying major and minor values) then call:
[locationManager startMonitoringForRegion:region];
To keep from going over your 20 region limit you also have to call:
[locationManager stopMonitoringForRegion:oldRegion];
On your old regions you do not want to monitor anymore. Otherwise if you go over the 20 limit you will not get detections on newly registered regions.
Of course, you may use a web service to provide the UUIDs for your new regions to monitor.
On Android it is much simpler -- you can monitor for all UUIDs by specifying a global wildcard using the Android Beacon Library and similar SDKs.
Full disclosure: I am the lead developer on the Android Beacon Library, the first beacon implementation on that platform.