CODEWITHSUNDEEP
iphoneobjective-clocation
Centurion
Centurion

Reputation: 14304

What is your experience about accuracy of core location services?

I need to estimate possible accuracy of iOS location services in airports. Does anyone have relative experience? There are noises and metal surroundings in airports, just curious what possible amount of accuracy it's possible to get when using cellular and GPS? IMHO even GPS might be not enough to track a user with an accuracy of meters when he is in tunnel or in lower grounds. Any thoughts and suggestions?

Upvotes: 0

Views: 648

Answers (2)

fishinear
fishinear

Reputation: 6336

I use BestForNavigation mode only in my app. If you are outside, then my experience is that the practical accuracy is actually a lot better than what is reported in the horizontalAccuracy field. Usually, practical horizontal accuracy is better than 5 meter. That is experience from various points in Europe (Sweden, Netherlands, Austria, Italy).

I have only seen accuracy problems when you are moving slowly (as in, walking speed). In that case, Apple does an "optimization": when the iPhone thinks you are standing still, it will freeze the location events. That is, it will report the exact same location in each event. It wil only report a new location after you have moved a substantial amount (in the order of 30-50 meter). I assume Apple does this to avoid jitter of a displayed map when standing still, but it is sure annoying when you are moving slowly.

Upvotes: 0

rckoenes
rckoenes

Reputation: 69469

Well you just have to do with the GPS and yes the accuracy isn't going to be precise to the meter.

You can get the accuracy from the CLLocation object in the – locationManager:didUpdateToLocation:fromLocation: delegate method of CLLocationManager:

- (void) locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {
    if (signbit(newLocation.horizontalAccuracy)) {
        dbgPrint(@"No location");
        return;
    }

    if (newLocation.horizontalAccuracy <= 200) {
       // new location is 200 meters in a circle.      
    }
}

Upvotes: 1

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