Question

I have a IOS app, that uses a network connection, and at times, it looses this network connection, whenever it does, I want the app to move back to a specific UIViewController.. What is the best way to achieve this?

Can I do this from the appDelegate?

Answer 1

Are you using the Reachability class described in the Apple documentation? If not, you should take a look at it. It will give you network status, including whether you are connected to the internet. It has a notification of network status change so you can put an observer in you app delegate or anywhere else you need it to accomplish your objective.

There is a lot of help already available on the web with examples on how to use Reachability, and this one may be something you can start with.

Update

Raachability change notifications can be used to inform your app when the connection is lost or restored. See the notification statement in the code below for the Reachability class;

static void ReachabilityCallback(SCNetworkReachabilityRef target, SCNetworkReachabilityFlags flags, void* info)

{

    #pragma unused (target, flags)

    NSCAssert(info != NULL, @"info was NULL in ReachabilityCallback");

    NSCAssert([(NSObject*) info isKindOfClass: [Reachability class]], @"info was wrong class in ReachabilityCallback");



    //We're on the main RunLoop, so an NSAutoreleasePool is not necessary, but is added defensively

    // in case someon uses the Reachablity object in a different thread.

    NSAutoreleasePool* myPool = [[NSAutoreleasePool alloc] init];



    Reachability* noteObject = (Reachability*) info;

    // Post a notification to notify the client that the network reachability changed.

    [[NSNotificationCenter defaultCenter] postNotificationName: kReachabilityChangedNotification object: noteObject];



    [myPool release];

}

For this to work you have to call startNotifier:

- (BOOL) startNotifier

{

    BOOL retVal = NO;

    SCNetworkReachabilityContext    context = {0, self, NULL, NULL, NULL};

    if(SCNetworkReachabilitySetCallback(reachabilityRef, ReachabilityCallback, &context))

    {

        if(SCNetworkReachabilityScheduleWithRunLoop(reachabilityRef, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode))

        {

            retVal = YES;

        }

    }

    return retVal;

}