gistfile1.m

CLLocationManager *manager = [[CLLocationManager alloc] init];
    if (manager.locationServicesEnabled == NO) {
        UIAlertView *servicesDisabledAlert = [[UIAlertView alloc] initWithTitle:@"Location Services Disabled" message:@"You currently have all location services for this device disabled. If you proceed, you will be asked to confirm whether location services should be reenabled." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [servicesDisabledAlert show];
        [servicesDisabledAlert release];
    }