iOS 7 CoreLocation: region monitoring fails on the first time after location services are authorised

Question

I identified a strange behaviour on my app using CoreLocation. I'm using the region monitoring functionality but, after authorising the location services (via popup or settings->Location Services) region monitoring fails (The operation couldn’t be completed. kCLErrorDomain error 5.). If I close the app and restart (therefore already authorised) everything works as expected. My code looks like this:

-(void)initializeLocationServices
{
    NSLog(@"Started location services");

    locationManager = [[CLLocationManager alloc] init];
    locationManager.delegate = self;
    locationManager.distanceFilter = kCLDistanceFilterNone;
    locationManager.desiredAccuracy = kCLLocationAccuracyBestForNavigation;
    locationManager.pausesLocationUpdatesAutomatically = NO;

    [locationManager startUpdatingLocation]; // to show authorisation popup
}

-(CLCircularRegion*)createRegion
{   
    // Test coordinates
    CLLocationDegrees latitude = 50;
    CLLocationDegrees longitude = -1;
    CLLocationDistance radius = 50; // meters;

    // If radius is too large, registration fails automatically, so limit the radius to the maximum value
    if (radius > locationManager.maximumRegionMonitoringDistance) {
        radius = locationManager.maximumRegionMonitoringDistance;
    }

    CLCircularRegion* region = [[CLCircularRegion alloc] initWithCenter:CLLocationCoordinate2DMake(latitude, longitude) radius:radius identifier:@"TEST"];

    region.notifyOnEntry = YES;
    region.notifyOnExit = YES;

    NSLog(@"Created region");

    return region;
}

-(void)monitorProximity
{
    CLRegion *region = [self createRegion];

    // Check if support is unavailable
    if ( ![CLLocationManager isMonitoringAvailableForClass:[CLRegion class]]) {
        NSLog( @"Failed to initialise region monitoring: support unavailable");
        return;
    }

    // Check if authorised
    if ([CLLocationManager authorizationStatus] != kCLAuthorizationStatusAuthorized) {
        NSLog( @"Failed to initialise region monitoring: app not authorized to use location services");
        return;
    } else {
        NSLog(@"Started monitoring proximity");
    }


    // Clear out any old regions to prevent buildup.
    if ([locationManager.monitoredRegions count] > 0) {
        for (id obj in locationManager.monitoredRegions)
            [locationManager stopMonitoringForRegion:obj];
    }

    [locationManager startMonitoringForRegion:region];
}

-(void)locationManager:(CLLocationManager *)manager didStartMonitoringForRegion:(CLRegion *)region
{
    NSLog(@"Started monitoring for region: %@", [region description]);
    [locationManager requestStateForRegion:region]; // check if already inside region
}

-(void)locationManager:(CLLocationManager *)manager monitoringDidFailForRegion:(CLRegion *)region withError:(NSError *)error
{
    NSLog(@"Failed to start monitoring for region: %@", [error localizedDescription]);
}


-(void)locationManager:(CLLocationManager *)manager didDetermineState:(CLRegionState)state forRegion:(CLRegion *)region
{
    NSLog(@"didDetermineState");

    if (state == CLRegionStateInside) {

        NSLog(@"inside");
        return;


    } else if (state == CLRegionStateOutside) {
        NSLog(@"outside");

    } else {
        NSLog(@"unknown");
    }

}

-(void)locationManager:(CLLocationManager *)manager didEnterRegion:(CLRegion *)region
{
    NSLog(@"didEnterRegion");
}

-(void)locationManager:(CLLocationManager *)manager didExitRegion:(CLRegion *)region
{
    NSLog(@"didExitRegion");
}

-(void)locationManager:(CLLocationManager *)manager didChangeAuthorizationStatus:(CLAuthorizationStatus)status
{
    NSLog(@"Monitoring authorisation status is now: %@", status == kCLAuthorizationStatusAuthorized ? @"authorized" : @"not authorized");

    if (status == kCLAuthorizationStatusAuthorized) {
        [self monitorProximity];
    }
}

Am I doing something wrong here? Do I have problems with the flow after didChangeAuthorizationStatus gets called?

Carlos P Carlos P · Accepted Answer · 2014-09-01T20:24:27

From other user reports, it seems that kCLErrorDomain 5 is a 'catch all' for region monitoring fails; it doesn't provide much useful information. I believe that your issue is being caused by the line

[locationManager requestStateForRegion:region]; // check if already inside region

which you're calling from inside the delegate method didStartMonitoringForRegion:

I saw something very similar in my own project and taking this line out (or delaying its execution for a while) solved the issue. My best guess is that iOS is still doing running some internal region monitoring code when this delegate method fires, so it's not an appropriate time to call requestStateForRegion:

Try taking this out and see if it is the answer.

iOS 7 CoreLocation: region monitoring fails on the first time after location services are authorised

3 Answers