To use standard location services while the application is in the background you need first turn on Background Modes in the Capabilities tab of the Target settings, and select Location updates.

#TODO: missing image, was http://cdn2.raywenderlich.com/wp-content/uploads/2014/12/background_modes.png

Or, add it directly to the Info.plist.

<key>NSLocationAlwaysUsageDescription</key>
<string>I want to get your location Information in background</string>

<key>UIBackgroundModes</key>
<array>
    <string>location</string>
</array>

Then you need to setup the CLLocationManager

Objective C

//The Location Manager must have a strong reference to it.
_locationManager = [[CLLocationManager alloc] init];
_locationManager.delegate = self;

//Request Always authorization (iOS8+)
if ([_locationManager respondsToSelector:@selector(requestAlwaysAuthorization)]) {
    [_locationManager requestAlwaysAuthorization];
}

//Allow location updates in the background (iOS9+)
if ([_locationManager respondsToSelector:@selector(allowsBackgroundLocationUpdates)]) {
    _locationManager.allowsBackgroundLocationUpdates = YES;
}

[_locationManager startUpdatingLocation];

Swift

self.locationManager.delegate = self

if #available (iOS 8.0,*) {
    self.locationManager.requestAlwaysAuthorization()
}

if #available (iOS 9.0,*) {
    self.locationManager.allowsBackgroundLocationUpdates = true
}

self.locationManager.startUpdatingLocation()