- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    NSLog(@"didFinishLaunching");

    // Get the device object and turn proximity monitoring on
    UIDevice *d = [UIDevice currentDevice];
    [d setProximityMonitoringEnabled:YES];

    // Get the NSNotificationCenter object
    NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];

    // Sign up to receive notifications when the proximity state changes
    [nc addObserver:self selector:@selector(proximityChanged:) name:UIDeviceProximityStateDidChangeNotification object:d];
    NSLog(@"Observing...");

    [self.window makeKeyAndVisible];
    return YES;

}

- (void)proximityChanged:(NSNotification *)note {

    // Print out the changes of proximity state
    NSLog(@"Proximity Changed: %d", [[note object] proximityState]);

}