Swift sometimes give this AppDelegate Error when try to find user location "Terminating app due to uncaught exception 'NSRangeException'.."

Question

Swift sometimes give this AppDelegate Error when try to find user location

*** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArray0 objectAtIndex:]: index 0 beyond bounds for empty NSArray'
*** First throw call stack:
(0x18b3fd1b8 0x189e3455c 0x18b367bac 0x1000ffd20 0x1000fe7f4 0x1000fea30 0x193400a38 0x1934002b4 0x1933f34b8 0x18b3aaa44 0x18b3aa240 0x18b3a8538 0x18b2d62b8 0x18cd8a198 0x19131d7fc 0x191318534 0x100108078 0x18a2b95b8)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb) 

This is my locationManager function:

 override func viewDidLoad() {
    super.viewDidLoad()
    locationManager.delegate = self
    locationManager.desiredAccuracy = kCLLocationAccuracyBest
    locationManager.requestAlwaysAuthorization()
    locationManager.startUpdatingLocation()               
}

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    let location = locations.last        
    myLat = (location?.coordinate.latitude)!
    myLng = (location?.coordinate.longitude)!        
    self.locationManager.stopUpdatingLocation()
    createMarker(lat: myLat,lng: myLng,zoom: 16)        
}

Sometimes its working good but sometimes the app crashes and give this AppDelegate error. So why I get this error and How I fix it?

Answer 1

You're assuming that the [CLLocation] array actually has elements, which isn't always true. Add an if let to conditionally process the location based on whether it is provided or not.

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    if let location = locations.last {
        myLat = location.coordinate.latitude
        myLng = location.coordinate.longitude
        self.locationManager.stopUpdatingLocation()
        createMarker(lat: myLat, lng: myLng, zoom: 16) 
    }
}