how to get location(coordinates) from city name in iphone sdk?

Question

friends,

as we have geocoder getfromlocation(locationname,maximumResults) function of google api in android.

i dont see such function in iphone sdk to obtain lat

Answer 1

iOS <5

There is no geocoding API. You need to ask Google: http://maps.googleapis.com/maps/api/geocode/json?address=YOURADDRESS&sensor=true and parse the result using JSONKit.

Something like this:

-(CLLocation*) geocodeAddress:(NSString*) address {

    NSLog(@"Geocoding address: %@", address);

    // don't make requests faster than 0.5 seconds
    // Google may block/ban your requests if you abuse the service
    double pause = 0.5;
    NSDate *now = [NSDate date];
    NSTimeInterval elapsed = [now timeIntervalSinceDate:self.lastPetition];
    self.lastPetition = now;
    if (elapsed>0.0 && elapsed1){
            NSLog(@"    There are %d possible results for this adress.", results);
        }
    }

    NSDictionary *locationDic = [[[[dic objectForKey:@"results"] objectAtIndex:0] objectForKey:@"geometry"] objectForKey:@"location"];
    NSNumber *latitude = [locationDic objectForKey:@"lat"];
    NSNumber *longitude = [locationDic objectForKey:@"lng"];    
    NSLog(@"    Google returned coordinate = { %f, %f }", [latitude floatValue], [longitude floatValue]);

    // return as location
    CLLocation *location = [[CLLocation alloc] initWithLatitude:[latitude doubleValue] longitude:[longitude doubleValue]];

    return [location autorelease];
}

+(NSDictionary*) parseJson:(NSString*) jsonString {

    NSDictionary *rootDict = nil;
    NSError *error = nil;
    @try {
        JKParseOptionFlags options = JKParseOptionComments | JKParseOptionUnicodeNewlines;
        rootDict = [jsonString objectFromJSONStringWithParseOptions:options error:&error];
        if (error) {
            warn(@"%@",[error localizedDescription]);
        }
        NSLog(@"    JSONKit: %d characters resulted in %d root node", [jsonString length], [rootDict count]);

    } @catch (NSException * e) {
        // If data is 0 bytes, here we get: "NSInvalidArgumentException The string argument is NULL"
        NSLog(@"%@ %@", [e name], [e reason]);

        // abort
        rootDict = nil;
    }
    return rootDict;
}

iOS >= 5

iOS 5 has a geocoder API:

CLGeocoder* gc = [[CLGeocoder alloc] init];
[gc geocodeAddressString:address completionHandler:^(NSArray *placemarks, NSError *error) 
{
    if ([placemarks count]>0) 
    {
        // get the first one
        CLPlacemark* mark = (CLPlacemark*)[placemarks objectAtIndex:0];
        double lat = mark.location.coordinate.latitude;
        double lng = mark.location.coordinate.longitude;            
    }
}];

The CLPlacemark object has the following properties:

• name
• addressDictionary: Address Book keys and values for the placemark.
• ISOcountryCode
• country
• postalCode
• administrativeArea
• subAdministrativeArea
• locality
• subLocality
• thoroughfare: Street address.
• subThoroughfare: Address Book keys and values for the placemark.
• region
• inlandWater
• ocean
• areasOfInterest