controller.m

if (asynchronous) //The asynchronous way, NOT WORKS (!!!) with IP addresses as host.
{
    //Set callback, dispatch callbacks on a background thread.
    SCNetworkReachabilitySetCallback(reachabilityRef, reachabilityCallback, &context);
    SCNetworkReachabilitySetDispatchQueue(reachabilityRef, dispatch_queue_create("com.eppz.reachability", nil));
}
else //The synchronous way, works well with IP addresses as host.
{
    //Get flags.
    SCNetworkReachabilityFlags flags;
    if (SCNetworkReachabilityGetFlags(reachabilityRef, &flags))
        [self.statusView showReachabilityFlags:flags];
}