How to check if location services are enabled for a particular app prior to iOS 4.2?

Question

How can I check if the user has allowed location for mu app? Normally I would use authorizationStatus method of the CLLocationManager class, but it

Answer 1

Hmm.. I didn't think to use authorizationStatus or locationServicesEnabled. What I did was the following:

MKUserLocation *userLocation = mapView.userLocation;

if (!userLocation.location) {
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Location Service Disabled" 
                                                    message:@"To re-enable, please go to Settings and turn on Location Service for this app." 
                                                   delegate:nil 
                                          cancelButtonTitle:@"OK" 
                                          otherButtonTitles:nil];
    [alert show];
    [alert release];
    return;
}

I'm glad to see there's a better method to check, but I haven't had any problems with the way I detect if my app is allowed to use the GPS.

Hope this helps!

Answer 2

When you call -startUpdatingLocation, if location services were denied by the user, the location manager delegate will receive a call to -locationManager:didFailWithError: with the kCLErrorDenied error code. This works both in all versions of iOS.

Answer 3

I've combined two techniques in the code below

    MKUserLocation *userLocation = map.userLocation;
    BOOL locationAllowed = [CLLocationManager locationServicesEnabled];
    BOOL locationAvailable = userLocation.location!=nil;

    if (locationAllowed==NO) {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Location Service Disabled" 
                                                        message:@"To re-enable, please go to Settings and turn on Location Service for this app." 
                                                       delegate:nil 
                                              cancelButtonTitle:@"OK" 
                                              otherButtonTitles:nil];
        [alert show];
        [alert release];
    } else {
        if (locationAvailable==NO) 
            [self.map.userLocation addObserver:self forKeyPath:@"location" options:(NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOld) context:nil];
    }