Online and offline support for RestKit iOS applications

You might use the Reachability Class to determine wether your client is offline or not. I use this great class very often in every project that requires an internet connection.

You simply start the notifier to a specific host. In all of your viewController you now just have to register methods to the NSNotificationCenter to set a BOOL isOnline for example.

Doing this practice you can do beautiful stuff in your app like overlaying the app with a smooth "Offline" message.

https://gist.github.com/1182373

EDIT

Heres one example from the login screen from one of my projects (sorry for this quantity of code but this is my complete implementation):

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{    //// Some stuff ////    [[Reachability reachabilityWithHostname:@"apple.com"] startNotifier];    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reachabilityChanged:) name:kReachabilityChangedNotification object:nil];}- (void)reachabilityChanged:(NSNotification *)note{    if ([[note object] isReachable]) {        CAKeyframeAnimation *scale = [CAKeyframeAnimation animationWithKeyPath:@"transform.scale"];        [scale setValues:[NSArray arrayWithObjects:[NSNumber numberWithFloat:1.0], [NSNumber numberWithFloat:0.0], nil]];        [scale setDuration:0.3];        [scale setRemovedOnCompletion:NO];        [[offlineView layer] setTransform:CATransform3DMakeScale(0, 0, 1.0)];        [[offlineView layer] addAnimation:scale forKey:@"scale"];        [[offlineView layer] setTransform:CATransform3DIdentity];        [UIView animateWithDuration:0.3 animations:^{            [offlineView setAlpha:0];        } completion:^(BOOL finished){            if (finished) {                [offlineView removeFromSuperview];            }        }];        [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleDefault animated:YES];    }    else {        CGRect screenFrame = CGRectMake(0, 0, 320, 480);        offlineView = [[UIView alloc] initWithFrame:screenFrame];        [offlineView setBackgroundColor:[UIColor colorWithWhite:0 alpha:0.7]];        [offlineView setAlpha:0];        offlineLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 200, 30)];        [offlineLabel setFont:[UIFont fontWithName:@"Verdana" size:30.0]];        [offlineLabel setBackgroundColor:[UIColor clearColor]];        [offlineLabel setTextAlignment:UITextAlignmentCenter];        [offlineLabel setTextColor:[UIColor whiteColor]];        [offlineLabel setCenter:[offlineView center]];        [offlineLabel setText:@"OFFLINE"];        [offlineView addSubview:offlineLabel];        [[self window] addSubview:offlineView];        [UIView animateWithDuration:0.3 animations:^{            [offlineView setAlpha:1.0];        }];        [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleBlackTranslucent animated:YES];    }}

Please check the version of RestKit; in the newer version of RestKit there is slightly changed approach of getting the cached data from managed object store.I don't have the example at this machine; but If you need help any more (since this a rather old question) please reply.