ObjcBlockExample3.m

//http://www.mikeash.com/?page=pyblog/friday-qa-2009-08-14-practical-blocks.html

// NSURLConnection
    @implementation NSURLConnection (BlocksAdditions)
    
    + (void)sendAsynchronousRequest: (NSURLRequest *)request
                    completionBlock: (void (^)(NSData *data, NSURLResponse *response, NSError *error))block
    {
        NSThread *originalThread = [NSThread currentThread];
        
        RunInBackground(^{
            WithAutoreleasePool(^{
                NSURLResponse *response = nil;
                NSError *error = nil;
                NSData *data = [self sendSynchronousRequest: request returningResponse: &response error: &error;];
                RunOnThread(originalThread, NO, ^{ block(data, response, error); });
            });
        });
    }
    
    @end

// Example:
  NSURLRequest *request = [NSURLRequest requestWithURL: [NSURL URLWithString: @"http://www.google.com/"]];
    [NSURLConnection sendAsynchronousRequest: request
                             completionBlock: ^(NSData *data, NSURLResponse *response, NSError *error){
        NSLog(@"data: %ld bytes  response: %@  error: %@", (long)[data length], response, error);
    }];