Completion blocks

gistfile1.txt

// How to create your own completion blocks

+ (void)responseFrom4sq:(CLLocation*)currentLocation limit:(NSString*)limit block:(void (^)(NSArray *locationDictionary, NSError *error))completionBlock{
        NSString *apiString4aq= @"https://api.foursquare.com/v2/venues/search?ll=";
        NSString *clientID = @"&client_id=x&client_secret=y";
        NSString *version = @"&v=20121219";
    
        NSMutableURLRequest *foursqRequest = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:[NSString stringWithFormat:@"%@%1.6f,%1.6f%@%@&limit=%@",apiString4aq,currentLocation.coordinate.latitude,currentLocation.coordinate.longitude,clientID,version,limit]]];
    
        dispatch_queue_t foursqQueue;
        foursqQueue = dispatch_queue_create("com.thePlayApp.foursqQueue", NULL);
        dispatch_async(foursqQueue, ^{
    
                NSURLResponse *response = nil;
                NSError *error = nil;
                NSError *error2 = nil;
 
                NSData *data = [NSURLConnection sendSynchronousRequest:foursqRequest
                                             returningResponse:&response
                                                         error:&error];
        if(!error){
                NSDictionary* json = [NSJSONSerialization
                              JSONObjectWithData:data
                              options:kNilOptions
                              error:&error2];
        
                if (!error2) {
            
                        NSLog(@"4sq data retrieved successfully");
            
                        NSDictionary *dataDictionary4sq = [json objectForKey:@"response"];
                        NSArray *venueArray = [dataDictionary4sq objectForKey:@"venues"];
            
                        completionBlock(venueArray,error);
            
                }else{
                        completionBlock([NSArray array] ,error);
                        NSLog(@"4sq data not retrieved successfully :(");
                }
        }else{
                completionBlock([NSArray array] ,error);
                NSLog(@"4sq data not retrieved successfully :(");
        }
   });
}


// How to deal with them

    [PlayUtility responseFrom4sq:_currentLocation limit:@"1" block:^(NSArray *locationDictionary, NSError *error) {
        if (!error){
            
            NSLog(@"in PlayUtility responseFrom4sq completed");
            dispatch_async(dispatch_get_main_queue(), ^(){
                [self getVenueData4sq:locationDictionary index:0];
            });
            
        }
    }];