ios - myLocationEnabled - Unexpectedly found nil while unwrapping -

i'm trying users location in mapviewcontroller using googlemaps api. i've looked around everywhere , can't figure out why continually getting fatal error: unexpectedly found nil while unwrapping , optional value in particular place.

here code:

class mapviewcontroller: uiviewcontroller {      let locationmanager = cllocationmanager()     @iboutlet weak var mapview: gmsmapview!      override func viewdidload() {         super.viewdidload()          locationmanager.delegate = self         locationmanager.requestwheninuseauthorization()          let camera = gmscameraposition.camerawithlatitude(-34.9290, longitude:138.6010, zoom:10)         let mapview = gmsmapview.mapwithframe(cgrectzero, camera:camera)         mapview.maptype = kgmstypenormal         print("calling addmarker")         // addmarker()         self.view = mapview         }  extension mapviewcontroller: cllocationmanagerdelegate {     func locationmanager(manager: cllocationmanager, didchangeauthorizationstatus status: clauthorizationstatus) {         if status == .authorizedwheninuse {             locationmanager.startupdatinglocation()             mapview.mylocationenabled = true             mapview.settings.mylocationbutton = true         }     }      func locationmanager(manager: cllocationmanager, didupdatelocations locations: [cllocation]) {         if let location = locations.first {             mapview.camera = gmscameraposition(target: location.coordinate, zoom: 15, bearing: 0, viewingangle: 0)             locationmanager.stopupdatinglocation()         }     } } 

this getting error:

!(http://imgur.com/qxxf0sv)

i mapview.mylocationenabled returning nil don't understand why/how.

most mapview nil, not mapview.mylocationenabled. when crash try following lldb command:

po mapview 

and tell exactly.

the didchangeauthorizationstatus delegate being called background or before view complete. should move extensions appdelegate.