iOS stops finding beacons when locking the screen - ios

Question

I write an app that uses beacons and everything is working fine when the app is in the foreground. However when I press the power button and dim the screen the app is not finding any beacons anymore. The app is still hitting the:
- (void)locationManager:(CLLocationManager *)manager didRangeBeacons:(NSArray *)clBeacons inRegion:(CLBeaconRegion *)region
method, but the logger tells me what 0 beacons has been found, which is weird, because due to the documentation, this methods should be called only when there are any beacons in range:
Tells the delegate that one or more beacons are in range.
I already have kCLAuthorizationStatusAuthorizedAlways permission from user (it's added to .plist file as well) and I have added these capabilities to the project:
This is my code for ranging beacons:
- (instancetype)init {
self = [super init];
if (self) {
NSUUID *proximityUUID = [[NSUUID alloc] initWithUUIDString:[Registry environment].config.beaconUuid];
self.region = [[CLBeaconRegion alloc] initWithProximityUUID:proximityUUID identifier:proximityUUID.UUIDString];
self.locationManager = [CLLocationManager new];
self.locationManager.delegate = self;
}
return self;
}
- (void)stopMonitoringBeacons {
[self.locationManager stopMonitoringForRegion:self.region];
DDLogInfo(#"Stopped monitoring beacons.");
}
- (void)locationManager:(CLLocationManager *)manager didStartMonitoringForRegion:(CLRegion *)region {
[manager requestStateForRegion:region];
[self startRangingBeacons];
}
- (void)startRangingBeacons {
[self.locationManager startRangingBeaconsInRegion:self.region];
DDLogInfo(#"Started ranging beacons.");
}
- (void)locationManager:(CLLocationManager *)manager rangingBeaconsDidFailForRegion:(CLBeaconRegion *)region withError:(NSError *)error {
DDLogInfo(#"Beacon ranging failed with error: %#.", error.localizedDescription);
}
- (void)locationManager:(CLLocationManager *)manager didRangeBeacons:(NSArray *)clBeacons inRegion:(CLBeaconRegion *)region {
DDLogDebug(#"Found %tu beacons.", clBeacons.count);
// call the server (no worries, not all the time)
}
Any idea what am I missing? Or maybe I can't trust these logs?
SOLVED:
The problem was the way I've tested it. As #davidgyoung mentioned, ranging works only in foreground and if we want to run it in background we need to start it from monitoring, which informs us about new beacons in background. I already did it in my code:
- (void)locationManager:(CLLocationManager *)manager didStartMonitoringForRegion:(CLRegion *)region {
[manager requestStateForRegion:region];
[self startRangingBeacons];
}
But this method is called only if we meet new beacon. I was already simulating beacon when my app was in foreground, so when I dimmed the screen with power button, ranging was stopped and monitoring was never called - I would have to turn the beacon off/on or walk out/in of the beacon range to call this method again.

Answer 1

Beacon ranging on iOS generally only works in the foreground, and for about 10 seconds after your app first moves to the background. Beacon monitoring on the other hand can work in the background and wake your app up when a beacon is detected. If you do both ranging and monitoring simultaneously, you will again get 10 seconds of background ranging after a monitoring trigger wakes your app up in the background.
You can extend background ranging from 10 seconds to 3 minutes on request. I wrote a blog post on how to do this.