gistfile1.m

- (void) connectUsingBlock:(void (^)(BOOL success, NSError *error))block {
    block = [block copy];
    
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,0),^(void){
        
        NSError *err = nil;
        BOOL success = YES;
        
        dispatch_async(dispatch_get_main_queue(),^ {
            block(success, err);
            [block release];
        });
        
    });
}

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
    [self connectUsingBlock:^(BOOL success, NSError *error) {
        NSLog(@"Succes: %d", success);
    }];
}