Forward geocoding support for ios4 and ios5

gistfile1.m

// Block param typedef
typedef void (^ForwardGeoCompletionBlock)(CLLocationCoordinate2D coords);

// Fetch Records Method

- (void)fetchForwardGeocodeAddress:(NSString *)address withCompletionHanlder:(ForwardGeoCompletionBlock)completion {
  
  if (NSClassFromString(@"CLGeocoder")) {
    
    CLGeocoder *geocoder = [[CLGeocoder alloc] init];
    
    CLGeocodeCompletionHandler completionHandler = ^(NSArray *placemarks, NSError *error) {
      
      if (error) {
        NSLog(@"error finding placemarks: %@", [error localizedDescription]);
      }
      
      if (placemarks) {
        
        [placemarks enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
          
          CLPlacemark *placemark = (CLPlacemark *)obj;
          
          NSLog(@"PLACEMARK: %@", placemark);
          
          if ([placemark.country isEqualToString:@"United States"]) {
            
            NSLog(@"********found coords for zip: %f %f", placemark.location.coordinate.latitude,placemark.location.coordinate.longitude);
            
            if (completion) {
              completion(placemark.location.coordinate);
            }
            
            *stop = YES;
          }
        }];
      }
    };
    
    [geocoder geocodeAddressString:address completionHandler:completionHandler];

  } else {

    /**
     * Since the request to grab the geocoded address is using NSString's initWithContentsOfURL 
     * we are going to make use of GCD and grab that async. I didn't put this in the 
     * method itself because there could be an instance where you would want to make a 
     * synchronous call. Better to have flexibility.
     *
     * Possible improvement could be to write another method that does the async 
     * loading for you. However, if you did it that way how would you be notified 
     * when the results returned. Possibly KVO?
     */
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0);

    dispatch_async(queue, ^{

      CLLocation *location = [address newGeocodeAddress];
      
      dispatch_async(dispatch_get_main_queue(), ^{

        if (completion) {
          completion(location.coordinate);
        }
      });
    });
  }
}

// NSString Category (JSONKit is dependency for project since there isn't a native parser in iOS4

@interface NSString (Additions)

- (CLLocation *)newGeocodeAddress;

@end

#import "NSString+Additions.h"

@implementation NSString (Additions)

- (CLLocation *)newGeocodeAddress {
  
  __block CLLocation *location = nil;
  
  NSString *gUrl = [NSString stringWithFormat:@"http://maps.googleapis.com/maps/api/geocode/json?address=%@&sensor=false", self];
  
  gUrl = [gUrl stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
  
  NSString *infoData = [[[NSString alloc] initWithContentsOfURL:[NSURL URLWithString:gUrl]
                                                       encoding:NSUTF8StringEncoding
                                                          error:nil] autorelease];
  
  if ((infoData == nil) || ([infoData isEqualToString:@"[]"])) {
    
    return location;
    
  } else {
    
    NSDictionary *jsonObject = [infoData objectFromJSONString]; 
    
    if (jsonObject == nil) {
      return nil;
    }
    
    NSArray *result = [jsonObject objectForKey:@"results"];
    
    [result enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
      
      NSDictionary *value = [[obj objectForKey:@"geometry"] valueForKey:@"location"];
      
      location = [[CLLocation alloc] initWithLatitude:[[value valueForKey:@"lat"] doubleValue]
                                            longitude:[[value valueForKey:@"lng"] doubleValue]];

      *stop = YES;
    }];  
  }   
  
  return location;
}

@end

// Request Execution

  [[MyLocationManager sharedManager] fetchForwardGeocodeAddress:@"37415" withCompletionHanlder:^(CLLocationCoordinate2D coords) {
    NSLog(@"found coords for zip: %f %f", coords.latitude, coords.longitude);
  }];