example of AFNetworking's nice wrapper to the Apple's hairy Reachability code.

gistfile1.m

        _reachability = [[AFHTTPClient alloc] initWithBaseURL:[NSURL URLWithString:@"http://api.rdio.com/"]];
        [_reachability setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {
            switch (status) {
                case AFNetworkReachabilityStatusNotReachable:
                    [self.reachabilityDelegate networkIsReachable:NO];
                    break;
                case AFNetworkReachabilityStatusReachableViaWiFi:
                case AFNetworkReachabilityStatusReachableViaWWAN:
                    [self.reachabilityDelegate networkIsReachable:YES];
                    break;
                case AFNetworkReachabilityStatusUnknown:
                    NSLog(@"AFNetworkReachabilityStatusUnknown");
                    break;
                default:
                    NSLog(@"not handled: %d", status);
                    break;
            }
        }];