Question

I’m creating an application which needs to determine if my current location (recd in didUpdateLocation:) is present among a set of geo-coordinates I have. Now I understand that comparing double/float values for equality can be error prone as the precisions involved in geo-coordinates is very high. Slight inaccuracy in the GPS can throw my algo off-track. Hence I need to compare it with some error margin.

How do I compare 2 CLLocations with a margin of error? Or determine the error in the location reading (I don’t think this is possible since CLLocationManager would have rectified it).

Thanks in advance 🙂

Answer 1

In each CLLocation instance there is a property declared as @property(readonly, nonatomic) CLLocationAccuracy horizontalAccuracy; What you can do is to make a routine like:

-(BOOL)isLocation:(CLLocation*)location inRangeWith:(CLLocation*)otherLocation{
    CLLocationDistance delta = [location distanceFromLocation:otherLocation];
    return (delta < location.horizontalAccuracy);
}

You can make even more complex logic as both locations have that property…

Cheers.
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