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

问题

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?

回答1:

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.

回答2:

kCLErrorDomain code/error 5 means that you have tried to monitor more than 20 CLRegions. Descriptio here

see startMonitoringForRegion description It says:
An app can register up to 20 regions at a time. In order to report region changes in a timely manner, the region monitoring service requires network connectivity.

回答3:

kCLErrorDomain 5 is a catch all that can mean many different things.

One of the sources is when you call [locationManager requestStateForRegion:region] which is necessary when you first monitor for a region to know if you're already in the region or not. This is because the didEnter region will only be called when you actually enter the region. Usually this means the first time you monitor for the region, you must wait 5 seconds until the region is not detected, and only then will didEnter region fire off the next time you're in the region.

There are many different reports of causes to the problem:

Ensure no more than 20 beacons are being monitored
5 means "regionMonitoringFailure". Ensure the radius is not too large (not relevant for beacon monitoring).
Ensure location updates are registered
Omit calling requestStateForRegion, however I described above why it's necessary to do so.
Restarting device and bluetooth may help
Try with 30 second delay

None of these worked for me, however. I think my root cause was similar to the iOS 7.1 bug where it just randomly stopped working on some devices. I tried the restart and restart of bluetooth, nothing helped.

Not sure what changed, but I just tried again the next day and it started working.

Basically you may want to try a different device until this one starts working again.

来源：https://stackoverflow.com/questions/22404620/ios-7-corelocation-region-monitoring-fails-on-the-first-time-after-location-ser

标签

ios

objective-c

ios7

core-location

region-monitoring