self.locationManager.location
is nil
since you never started updating the location.
In the apple docs it is stated about the location
property of the locationManager:
The value of this property is nil if no location data has ever been retrieved.
For this reason you need to somehow update your iPhones location!
Usually this means you want to call
[self.locationManager startUpdatingLocation]
but you can also use
[self.locationManager startMonitoringSignificantLocationChanges]