Specifies whether ___location service is enabled in user settings.
You should check this property before starting ___location updates to
determine if the user has ___location services enabled for the current
device.
On iOS, if this property is false and you start ___location updates
anyway, the CoreLocation framework prompts the user with a confirmation
panel asking whether ___location services should be reenabled. The user
can enable or disable ___location services altogether from the Settings
application by toggling the switch in
Settings>General>LocationServices.