Distance to a location while user is in motion

Question

I\'m in the process of writing an application that shows the user\'s distance from a fixed point as the user walks around (i.e. the label showing the distance from the user

Answer 1

Are you filtering out old (cached) positions? You should also filter based on accuracy, you probably don't want low accuracy locations.

You won't get continous or periodic update, the callback only occurs when the location has changed.

Assuming the device has GPS and can see enough GPS satellites to get a good position, this works fine.

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

    NSTimeInterval age = -[newLocation.timestamp timeIntervalSinceNow]; 

    if (age > 120) return;    // ignore old (cached) updates

    if (newLocation.horizontalAccuracy < 0) return;   // ignore invalid udpates

    ...
}