Waiting on a gcd task in a command line app

main.m

#import <Foundation/Foundation.h>

NSString *const retirementUrl = @"https://query.yahooapis.com/v1/public/yql/homerj/retirement?format=json";


int main(int argc, const char * argv[]) {
    @autoreleasepool {
        // insert code here...
        NSURLSession *session = [NSURLSession sharedSession];
        
        dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
        
        [[session dataTaskWithURL:[NSURL URLWithString:retirementUrl]
                completionHandler:^(NSData *data,
                                    NSURLResponse *response,
                                    NSError *error) {
                    NSLog(@"in the callback");
                    NSHTTPURLResponse *httpResponse  = (NSHTTPURLResponse*)response;
                    if(!error) {
                        NSError *jsonError;
                        NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data
                                                                             options:NSJSONReadingAllowFragments
                                                                               error:&jsonError];
                        if(!jsonError) {
                            NSString *body;
                            NSLog(@"response code:\t%ld", (long)httpResponse.statusCode);
                            NSLog(@"%@", body=(NSString*)[json valueForKeyPath:@"query.results.html.body"]);
                            
                            NSMutableDictionary *results = [@{} mutableCopy];
                            [[body componentsSeparatedByString:@"&"]
                             enumerateObjectsUsingBlock:^(NSString *obj, NSUInteger idx, BOOL *stop) {
                                 NSArray *components = [obj componentsSeparatedByString:@"="];
                                 NSLog(@"component.count == %ld", components.count);
                                 if(components.count > 1) {
                                     results[components[0]] = [components[1] stringByTrimmingCharactersInSet:
                                                               [NSCharacterSet whitespaceAndNewlineCharacterSet]
                                                               ];
                                 }
                             }];
                            NSLog(@"results = %@", results);
                            NSLog(@"filtering for powerball");
                            NSSet *powerball = [results keysOfEntriesPassingTest:^BOOL(id key, id obj, BOOL *stop) {
                                if([key hasPrefix:@"powerball"]) {
                                    return YES;
                                }
                                return NO;
                            }];
                            NSLog(@"found %ld powerball entries", powerball.count);
                            NSSet *megamillions = [results keysOfEntriesPassingTest:^BOOL(id key, id obj, BOOL *stop) {
                                if([key hasPrefix:@"biggame"]) {
                                    return YES;
                                }
                                return NO;
                            }];
                            NSLog(@"found %ld megamillions entries\n\n%@", megamillions.count, megamillions);
                        }
                    }
                    dispatch_semaphore_signal(semaphore);
                    
                }] resume];
        
        NSLog(@"waiting");
        long rc = dispatch_semaphore_wait(semaphore, dispatch_time(DISPATCH_TIME_NOW, 60.0 * NSEC_PER_SEC));
        NSLog(@"rc == %ld", rc);
    }
    
    return 0;
}