Web service for Location name using Latitude & Longtitude

Question

I have an iPhone application where i need to find out the current location(in terms of city name or probably the address). But i'm not been able to do that. I can find out the current latitude and longitude. Is there any web service(preferably free of cost) which can return me the current location name if i supply the latitude and longitude?

Waiting For any reply.

Thanks in advance..

Joy

Answer 1

The feature you're looking for is called Reverse Geocoding.

Here is a list of web services that provide this function.

A couple of the most popular are Geonames.org, Google Maps Services API and Batchgeo.com for batch processing of multiple coordinates.

Answer 2

Assuming you are targeting iPhone OS 3.0 or higher, you can use MKReverseGeocoder which is part of the MapKit Framework. The Developer docs include a sample project. MKReverserGeocoder Class Reference

Answer 3

MKReverseGeocoder is a great class, but sometimes may return the error: Error Domain=PBRequesterErrorDomain Code=6001 "Operation could not be completed. (PBRequesterErrorDomain error 6001.)

luvieere's suggestion above are a great place to start, which is what I did as an example using the Google HTTP reverse geocoder. Here's my implementation of a GoogleReverseGeocoder class I wrote. The full explanation of how to use it can be found HERE.

// Send Google A Request
NSString *urlString = [NSString stringWithFormat:@"http://maps.google.com/maps/geo?q=%lf,%lf&output=csv&sensor=false",self.locationToGeocode.coordinate.latitude,self.locationToGeocode.coordinate.longitude];
NSURL *urlFromString = [NSURL URLWithString:urlString];
NSStringEncoding encodingType = NSUTF8StringEncoding;
NSString *reverseGeoString = [NSString stringWithContentsOfURL:urlFromString encoding:encodingType error:nil];

// Parse Out Response
NSArray *listItems = [reverseGeoString componentsSeparatedByString:@","];
NSArray *tempAddressArray = [[listItems objectAtIndex:2] componentsSeparatedByString:@"\""];
NSArray *tempCountryArray = [[listItems objectAtIndex:[listItems count]-1] componentsSeparatedByString:@"\""];

// Did Google Find Address? 200 is yes
if ([[listItems objectAtIndex:0] intValue] == 200)
{
    // Set Class Member Variables
    [self setGoogleReturnDidFindAddress:YES];
    [self setGoogleReturnAddress:[tempAddressArray objectAtIndex:[tempAddressArray count]-1]];
    [self setGoogleReturnCountry:[tempCountryArray objectAtIndex:0]];
    [self setGoogleReturnCode:[[listItems objectAtIndex:0] intValue]];
    [self setGoogleReturnAccuracy:[[listItems objectAtIndex:1] intValue]];

} else if ([[listItems objectAtIndex:0] intValue] > 600)
{
    [self setGoogleReturnDidFindAddress:NO];
}