NSRangeException - ne peut pas supprimer observateur

Question

Je suis en train de capturer des images et enregistrer des vidéos de caméra, mais chaque fois que je rejette mon point de vue avec caméra je reçois cette erreur:

Terminating app due to uncaught exception 'NSRangeException', reason: 'Cannot remove an observer App.CameraViewController 0x16ea7f70 for the key path "movieFileOutput.recording" from App.CameraViewController 0x16ea7f70 because it is not registered as an observer.' *** First throw call stack: (0x2a9e6fef 0x3908ac8b 0x2a9e6f35 0x2b6850f5 0x2b684b07 0x2b6849ab 0xbeb40 0xbca88 0x85c173 0x864d67 0x85ea61 0x866b09 0x867e19 0x39782dc1 0x39782b14) libc++abi.dylib: terminating with uncaught exception of type NSException

Mon code:

class CameraViewController: UIViewController, CameraDelegate, AVCaptureFileOutputRecordingDelegate { 

    // MARK: 
    // MARK: - Property 
    @IBOutlet weak var captureButton: UIButton! 
    @IBOutlet var previewView: CameraPreviewView! 

    weak var cameraDelegate: CameraDelegate? 

    var sessionQueue: dispatch_queue_t? 
    var captureSession: AVCaptureSession? 
    var stillImageOutput: AVCaptureStillImageOutput? 
    var videoDeviceInput: AVCaptureDeviceInput? 
    var movieFileOutput: AVCaptureMovieFileOutput? 

    var previewLayer: AVCaptureVideoPreviewLayer? 

    var deviceAuthorized: Bool = false 
    var backgroundRecordId: UIBackgroundTaskIdentifier = UIBackgroundTaskInvalid 
    var sessionRuningAndDeviceAuthorized: Bool { 
     get { 
      return (self.captureSession?.running != nil && self.deviceAuthorized) 
     } 
    } 
    var runtimeErrorHandlingObserver: AnyObject? 
... 
} 

Ajout observateurs:

override func viewWillAppear(animated: Bool) { 
     super.viewWillAppear(animated) 

     dispatch_async(self.sessionQueue!, { 
      // TODO: Make constants 
      self.addObserver(self, forKeyPath: "sessionRunningAndDeviceAuthorized", options: NSKeyValueObservingOptions.Old | NSKeyValueObservingOptions.New, context: &SessionRunningAndDeviceAuthorizedContext) 
      self.addObserver(self, forKeyPath: "stillImageOutput.capturingStillImage", options: NSKeyValueObservingOptions.Old | NSKeyValueObservingOptions.New, context: &CapturingStillImageContext) 
      self.addObserver(self, forKeyPath: "movieFileOutput.recording", options: NSKeyValueObservingOptions.Old | NSKeyValueObservingOptions.New, context: &RecordingContext) 


      NSNotificationCenter.defaultCenter().addObserver(self, selector: "subjectAreaDidChange:", name: AVCaptureDeviceSubjectAreaDidChangeNotification, object: self.videoDeviceInput?.device) 

      weak var weakSelf = self 

      self.runtimeErrorHandlingObserver = NSNotificationCenter.defaultCenter().addObserverForName(AVCaptureSessionRuntimeErrorNotification, object: self.captureSession, queue: nil, usingBlock: { 
       (note: NSNotification?) in 
       var stronSelf: CameraViewController = weakSelf! 
       dispatch_async(stronSelf.sessionQueue!, { 
        if let sess = stronSelf.captureSession { 
         sess.startRunning() 
        } 
       }) 

      }) 

      self.captureSession?.startRunning() 
     })          
    } 

et le code avec la suppression des observateurs:

override func viewWillDisappear(animated: Bool) { 
     super.viewWillDisappear(animated) 

     dispatch_async(self.sessionQueue!, { 

      if let sess = self.captureSession { 
       sess.stopRunning() 

       NSNotificationCenter.defaultCenter().removeObserver(self, name: AVCaptureDeviceSubjectAreaDidChangeNotification, object: self.videoDeviceInput?.device) 
       NSNotificationCenter.defaultCenter().removeObserver(self.runtimeErrorHandlingObserver!) 

       // TODO: Make constants 

       self.removeObserver(self, forKeyPath: "sessionRunningAndDeviceAuthorized", context: &SessionRunningAndDeviceAuthorizedContext) 
       self.removeObserver(self, forKeyPath: "stillImageOutput.capturingStillImage", context: &CapturingStillImageContext) 
       self.removeObserver(self, forKeyPath: "movieFileOutput.recording", context: &SessionRunningAndDeviceAuthorizedContext) 

      } 
     }) 
    } 

Answer 1

Vous utilisez le mauvais contexte dans removeObserver(...)

Aussi, pourquoi vous supprimez les observateurs dans un bloc asynchrone?