ios - didUpdateToLocation called twice, ok. Why is oldLocation nil both times? -

i understand cllocationmanager called twice on init in cases, once cached location data, , once updated content.

this makes sense, when returns same result in both cases (eg: because simulated location returns same coord , accuracy).

here log startup process. didupdatetolocation called twice, both times oldlocation nil:

// setup code: let locationmanager = cllocationmanager() locationmanager.delegate = self locationmanager.distancefilter = 100.0 locationmanager.requestwheninuseauthorization() locationmanager.startupdatinglocation()  // log output: locationmanager didupdatetolocation  old: nil  new: <+22.28468100,+114.15817700> +/- 5.00m (speed -1.00 mps / course -1.00) @ 6/25/15, 3:21:57 pm indochina time  locationmanager didupdatetolocation  old: nil  new: <+22.28468100,+114.15817700> +/- 5.00m (speed -1.00 mps / course -1.00) @ 6/25/15, 3:22:01 pm indochina time 

what doesn't make sense oldlocation nil in these cases. have provide external variable call actualoldlocation keep track of change in distance between updates. doing wrong causes value nil?

what ios targeting? didupdatetolocation deprecated ios 6.0, not sure works nowadays.