Current Location Bug in Xcode 4.5

Question

In Xcode 4.5 apple introduced apple new maps. My application heavliy requires map services. And I have noticed in my application it shows the wrong current location until yo

Answer 1

you should check the timestamp .. if i understand your app logic correctly, you could do something like -

- (void)locationManager:(CLLocationManager *)manager
    didUpdateToLocation:(CLLocation *)newLocation
           fromLocation:(CLLocation *)oldLocation {

NSDate* time = newLocation.timestamp;
    NSTimeInterval timePeriod = [time timeIntervalSinceNow];
    if(timePeriod < SOME_MINIMUM_TIME_PERIOD ) { //for eg: timePeriod < 1.0
               totalDistance += [newLocation distanceFromLocation:oldLocation];
    } else {
        // skip.. or do what you do on a 'location-not-updated' event
    }
}

Answer 2

I have noticed the same problem with Xcode 4.4+. The problem only occurs (randomly, or so it seems) within Xcode: if you upload the app to the App Store, this is not a problem anymore. In the meantime, please file a bug.

Answer 3

The old approach from apple docs seems still working in iOS6 (didn't notice this in my active app (it tracks user's route via gps))

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {

    NSTimeInterval locationAge = -[newLocation.timestamp timeIntervalSinceNow];
    if (locationAge > 5.0) return;
    if (newLocation.horizontalAccuracy < 0) return; 

    // proceed with coords here
}

UPDATE from the discussion: Calculating total and current distance could be done like this (excluding some minor stuff):

// somewhere at the top
CLLocation* lastUsedLocation = nil; // last location used in calculation
CLLocation* pointA = nil;  // start of the track
double totalDistance = 0;  // total distance of track
double currentDistance = 0; // distance between startTrack point and current location
...

// when you start updating location:
- (void) startTracking {
    lastUsedLocation = nil;
    pointA = nil;
    totalDistance = 0;
    currentDistance = 0;
    [locationManager startUpdatingLocation];
}
...


// location update callback
 - (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation { 
    NSTimeInterval locationAge = -[newLocation.timestamp timeIntervalSinceNow]; 
    if (locationAge > 5.0) return;  // filter cached
    if (newLocation.horizontalAccuracy < 0) return; // filter invalid

    if(!pointA) pointA = [newLocation retain]; 

    if(lastUsedLocation) 
    { 
        totalDistance += [newLocation distanceFromLocation:lastUsedLocation]; 
    } 
    currentDistance = [pointA distanceFromLocation:newLocation]; 
    [lastUsedLocation release]; 
    lastUsedLocation = [newLocation retain]; 
}

If you need the option to turn off background location on purpose you disable it manually like:

- (void)applicationDidEnterBackground:(UIApplication *)application {
    if(backgroundLocationDisabled)
    {
        [locationManager stopUpdatingLocation];
        // additional stuff
    }
}