Question

I want to show user’s current location with iphone gps feature but problem is it is giving incorrect location .
When i drop pin on map then it drops pin at exact position but when i try to see the location in text then it gives inaccurate location with inaccuracy of 500 to 800 meters approx.I have used reverse geocoding and google api but all giving same location. PLease tell me why this happens and how can i show the exact location of user ?
My code is:

cllocationmanager *locationManager = [[CLLocationManager alloc] init];
        locationManager.delegate = self;
        locationManager.distanceFilter = kCLDistanceFilterNone; // whenever we move
        locationManager.desiredAccuracy = kCLLocationAccuracyBest; // 100 m
        [locationManager startUpdatingLocation];


    }

    }



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

{


 CLLocationCoordinate2D here =  newLocation.coordinate;
    NSLog(@"%f  %f ", here.latitude, here.longitude);


    MKReverseGeocoder *geocoder = [[MKReverseGeocoder alloc] initWithCoordinate:here];
    [geocoder setDelegate:self];
    [geocoder start];

        }



- (void)reverseGeocoder:(MKReverseGeocoder *)geocoder didFailWithError:(NSError *)error{



}



- (void)reverseGeocoder:(MKReverseGeocoder *)geocoder didFindPlacemark:(MKPlacemark *)placemark
{
    NSLog(@"The geocoder has returned: %@", [placemark addressDictionary]);



    UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Error" message:[NSString stringWithFormat:@"%@",[placemark addressDictionary]] delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [alertView show];
    [alertView release];


}

Answer 1

Quick guess: did you check the CLLocation’s horizontal accuracy? Quite often the first response I get is very inaccurate, and then subsequent calls get better.

Edit: @pankaj First of all, can you confirm that it is an accuracy issue. If it is the problem that I’m suggesting, then the CLLocation horizontalAccuracy will be large. If not the case then you can ignore my answer and these comments. However, if horizontalAccuracy is a large error then you will have to wait for a better lock. There are two ways to do this:

1. Wait for a short period of time (a second or two) and see if you get a better lock.
2. Start requesting location much earlier on, e.g. when the app launches, or when the UIViewController that requires location starts.