How to detect compass calibration switch state on iOS

cllocationmanager, core-location, heading, ios

Solution

From what I've found, `newHeading.trueHeading` in `locationManager:didUpdateHeading:` should be `-1` if compass calibration is turned off. This should do it:

- (void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading
{
    if(newHeading.trueHeading == -1)
        //Compass calibration is off provided location services are on for the app
}

Problem

I am currently working with the `CLLocationManager` and want to get informed about the current heading of the device. So far everything works fine, features are implemented and now i try to polish my app. There is a corner case, if the user will turn off the `compass calibration` flag in the user settings heading updates will not be send any more to my app. In such a case I want to give the user some feedback, that he has to turn on compass calibration again otherwise my app will not work. I figured out that in case of the user turns off the `location services` for my app I will still receive magnetic heading. But if the "compass calibration" setting will be turned of by the user I will not receive any longer heading updates. But how can i identify through the `CoreLocation` framework that "compass calibration" was turned off? The "`CLLocationManagerDelegate`" gives me an update through the ``` - (void)locationManager:(CLLocationManager*)manager didChangeAuthorizationStatus:(CLAuthorizationStatus)status ``` method. But the status indicates only if the "location services" is in-/active for my app. I also tried to get some valid informations through the ``` - (void)locationManager:(CLLocationManager*)manager didFailWithError:(NSError*)error ``` `delegate` method, without any success. Is there something in the `CoreLocation` framework that can tell me if "compass calibration" flag is turned on/off.

Original source