HTTPLoader @ http://satoshi.blogs.com/life/2012/08/block.html

HTTPLoader.h

#import <Foundation/Foundation.h>

typedef void(^HTTPLoaderCompleteBlock)(NSData *data, NSError *error);

@interface HTTPLoader : NSObject

+(void)loadAsync:(NSURLRequest *)request complete:(HTTPLoaderCompleteBlock)completion;

@end

HTTPLoader.m

#import "HTTPLoader.h"

@implementation HTTPLoader

+(void)loadAsync:(NSURLRequest *)request complete:(HTTPLoaderCompleteBlock)completion
{
    dispatch_queue_t currentQueue = dispatch_get_current_queue();
    
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSError *error = nil;
        NSURLResponse *response = nil;
        
        NSData *receivedData = [NSURLConnection sendSynchronousRequest:request
                                                     returningResponse:&response
                                                                 error:&error];
        
        dispatch_async(currentQueue, ^{
            if (completion) {
                completion(receivedData, error);
            }
        });
    });
}

@end