CLLocationManager tracks wrong Location (Track Me) - iphone

Question

I am implementing Track me option in my code.CLLocationManager is not working as expected.when I start app remain at the same position ,CLLocationManager changes around 20-30 meters with-in 1 min minutes..then I remain Constant.
And If i change my position to track same thing happen in starting 1 min CLLocationManager moves 20-30 min extra then moves with my speed..
Why this happening..
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.delegate = self;
self.locationManager.distanceFilter = 0.0001;
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
}
-(void)start {
[self.locationManager startUpdatingLocation];
}
- (void)locationManager:(CLLocationManager*)manager
didUpdateToLocation:(CLLocation*)newLocation
fromLocation:(CLLocation*)oldLocation {
[self processLocationChange:newLocation fromLocation:oldLocation];
}
-(void)processLocationChange:(CLLocation*)newLocation fromLocation:oldLocation {
if (newLocation != oldLocation) {
NSLog(#"Moved from %# to %#", oldLocation, newLocation);
CLLocation* lastKnownLocation = NULL;
if ([self.locationPoints count] > 0) {
lastKnownLocation = [self.locationPoints objectAtIndex:[self.locationPoints count] - 1];
}
else {
lastKnownLocation = newLocation;
self.bottomLeft = newLocation.coordinate;
self.topRight = newLocation.coordinate;
}
// Check for new boundaries
CLLocationCoordinate2D coords = newLocation.coordinate;
if (coords.latitude < bottomLeft.latitude || coords.longitude < bottomLeft.longitude) {
self.bottomLeft = coords;
NSLog(#"Changed bottom left corner");
}
if (coords.latitude > topRight.latitude || coords.longitude > topRight.longitude) {
self.topRight = coords;
NSLog(#"Changed top right corner");
}
double speed = fabs(newLocation.speed);
double deltaDist = fabs([newLocation distanceFromLocation:lastKnownLocation]);
double newAvgSpeed = (self.totalDistance + deltaDist) / ((double)[self getElapsedTimeInMilliseconds] / 1000.0);
double accuracy = newLocation.horizontalAccuracy;
double alt = newLocation.altitude;
NSLog(#"Change in position: %f", deltaDist);
NSLog(#"Accuracy: %f", accuracy);
NSLog(#"Speed: %f", speed);
NSLog(#"Avg speed: %f", newAvgSpeed);
self.totalDistance += deltaDist;
self.currentSpeed = speed;
self.avgSpeed = newAvgSpeed;
self.altitude = alt;
NSLog(#"Delta distance = %f", deltaDist);
NSLog(#"New distance = %f", self.totalDistance);
// Add new location to path
[self.locationPoints addObject:newLocation];
// Update stats display
[self.first.start1 updateRunDisplay];
// Update map view
[self updateMap:lastKnownLocation newLocation:newLocation];
}
}

Answer 1

I faced the same problem in my current Pedometer app. I stretched, banged my head for couple of days. Then I found out that CLLocationManager is not able to track <5 meter distance and location generate updates. I kept self.locationManager.distanceFilter =2.0; and it gave me location updates even device was stationary. So I just changed distancefilter to 5.0 meter and it started working great. Try taking 5 meters it should work, I tested and all my wrong notifications issues vanished:
self.locationManager.distanceFilter =5.0;
You are taking self.locationManager.distancefilter=0.0001 which is I suppose out of capacity for CLLocationManager to track such a minor movement. Also you need to filter out old locations i.e. cached location updates as mentioned in Location Awareness Guide by Apple. I have used this condition in my code to filter all events which are older than 5 seconds.
- (void)locationManager:(CLLocationManager *)manager
didUpdateLocations:(NSArray *)locations
{
CLLocation *currentLocation=[locations lastObject];
NSDate* eventDate = currentLocation.timestamp;
NSTimeInterval howRecent = [eventDate timeIntervalSinceNow];
if(abs(howRecent)<5.0 && self.currentLocation.horizontalAccuracy<=10 && self.currentLocation.horizontalAccuracy>0)
{
//you have got fresh location event here.
}
}

Answer 2

I think give the distance filter effective with this
self.locationManager.distanceFilter = kCLDistanceFilterNone;
and you can start updating location method but also try this method these both methods are required to get exact location
[locationManager startMonitoringSignificantLocationChanges];