Notification when wifi connected (OS X) - objective-c

Question

I need a notification from the system when airport is connecting to an ap. Is there any possibility to do that with the SystemConfiguration framework? I have problems to understand the systemconfigurations api documentation.

Answer 1

You are on the right track with the SystemConfiguration network, which offers the SCNetworkReachability set of functions. You could try using
SCNetworkReachabilitySetCallback
to set a callback which will be called when the reachability changes; and
SCNetworkReachabilityScheduleWithRunLoop
to schedule the reachability check within the run loop
Or you might try using a reachability framework (both for MacOS and iOS) which is built on top of the SystemConfiguration framework to make things even easier (higher-level).
If you want to go the SystemConfiguration way, this is how you check for present reachability and install the callback to be notified of changes (source):
- (void)checkReachability {
NSString *server = [[NSUserDefaults standardUserDefaults] stringForKey:#"NCIDServer"];
if (server == nil) {
ncid_message_callback(self, [NSLocalizedString(#"No caller ID server was specified.", nil) UTF8String]);
return;
}
const char *serverName = [[[server componentsSeparatedByString:#":"] objectAtIndex:0] UTF8String];
SCNetworkReachabilityContext context = {0, (void *)self, NULL, NULL, NULL};
networkReachability = SCNetworkReachabilityCreateWithName(NULL, serverName);
if (networkReachability == NULL)
goto fail;
// If reachability information is available now, we don't get a callback later
SCNetworkConnectionFlags flags;
if (SCNetworkReachabilityGetFlags(networkReachability, &flags))
networkReachabilityCallback(networkReachability, flags, self);
if (!SCNetworkReachabilitySetCallback(networkReachability, networkReachabilityCallback, &context))
goto fail;
if (!SCNetworkReachabilityScheduleWithRunLoop(networkReachability, [[NSRunLoop currentRunLoop] getCFRunLoop], kCFRunLoopCommonModes))
goto fail;
return;
fail:
if (networkReachability != NULL)
CFRelease(networkReachability);
networkReachability = NULL; //-- ivar representing current reachability
}
And this is a sample of the callback:
static void networkReachabilityCallback(SCNetworkReachabilityRef target,
SCNetworkConnectionFlags flags,
void *object) {
// Observed flags:
// - nearly gone: kSCNetworkFlagsReachable alone (ignored)
// - gone: kSCNetworkFlagsTransientConnection | kSCNetworkFlagsReachable | kSCNetworkFlagsConnectionRequired
// - connected: kSCNetworkFlagsIsDirect | kSCNetworkFlagsReachable
if (networkReachability == NULL)
return;
if ((flags & kSCNetworkFlagsReachable) && !(flags & kSCNetworkFlagsConnectionRequired)) {
if (isReachable) // typically receive a reachable message ~20ms before the unreachable one
return;
isReachable = YES;
ncid_network_kill();
[NSThread detachNewThreadSelector:#selector(runThread:) toTarget:object withObject:nil];
} else {
isReachable = NO;
ncid_network_kill();
}
}

Answer 2

You need to use Apple's Reachability class for this. http://developer.apple.com/library/ios/#samplecode/Reachability/Listings/Classes_Reachability_m.html#//apple_ref/doc/uid/DTS40007324-Classes_Reachability_m-DontLinkElementID_6
You can check this thread for how to use this class-
How do I receive notifications that the connection has changed type (3G, Edge, Wifi, GPRS)