[iOS] 네트워크 연결 테스트 (wifi, cell)

- (void)viewDidLoad
{
    [super viewDidLoad];

    NSString *results = [NSString stringWithFormat:@"네트워크 사용 %@가능 %@%@",
    ([UIDevice networkAvailable] ? @"" : @"불"),
    ([UIDevice activeWLAN] ? @"[WiFi]" : @""),
    ([UIDevice activeWWAN] ? @"[Cell]" : @"")];
    self.lbl_txt.text = results;

}    



+ (NSString *) localWiFiIPAddress
{
    BOOL success;
    struct ifaddrs * addrs;
    const struct ifaddrs * cursor;
    success = getifaddrs(&addrs) == 0;
    if (success) {
        cursor = addrs;
        while (cursor != NULL) {
            // the second test keeps from picking up the loopback address
           if (cursor->ifa_addr->sa_family == AF_INET && (cursor->ifa_flags & IFF_LOOPBACK) == 0)
            {
                NSString *name = [NSString stringWithUTF8String:cursor->ifa_name];
                if ([name isEqualToString:@"en0"])  // Wi-Fi adapter
                    return [NSString stringWithUTF8String:inet_ntoa(((struct sockaddr_in *)cursor->ifa_addr)->sin_addr)];
            }
            cursor = cursor->ifa_next;
        }
        freeifaddrs(addrs);
    }
    return nil;
}


#pragma mark Checking Connections

+ (void) pingReachabilityInternal
{
    BOOL ignoresAdHocWiFi = NO;
    struct sockaddr_in ipAddress;
    bzero(&ipAddress, sizeof(ipAddress));
    ipAddress.sin_len = sizeof(ipAddress);
    ipAddress.sin_family = AF_INET;
    ipAddress.sin_addr.s_addr = htonl(ignoresAdHocWiFi ? INADDR_ANY : IN_LINKLOCALNETNUM);
    
    // Recover reachability flags
    SCNetworkReachabilityRef defaultRouteReachability = SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault, (struct sockaddr *)&ipAddress);
/* SCNetworkReachabilityGetFlags :  if the given target is reachable using the current network configuration. */
    BOOL didRetrieveFlags = SCNetworkReachabilityGetFlags(defaultRouteReachability, &connectionFlags);
    CFRelease(defaultRouteReachability);
    if (!didRetrieveFlags)
        printf("Error. Could not recover network reachability flags\n");
}

+ (BOOL) networkAvailable
{
    [self pingReachabilityInternal];
    BOOL isReachable = ((connectionFlags & kSCNetworkFlagsReachable) != 0);
    BOOL needsConnection = ((connectionFlags & kSCNetworkFlagsConnectionRequired) != 0);
    return (isReachable && !needsConnection) ? YES : NO;
}

+ (BOOL) activeWWAN
{
    if (![self networkAvailable]) return NO;
    return ((connectionFlags & kSCNetworkReachabilityFlagsIsWWAN) != 0);
}

+ (BOOL) activeWLAN
{
    return ([UIDevice localWiFiIPAddress] != nil);
}