     
     private var currentCameraDevice:AVCaptureDevice?
     
-    private var sessionQueue:dispatch_queue_t = dispatch_queue_create("com.example.session_access_queue", DISPATCH_QUEUE_SERIAL)
+    private var sessionQueue:dispatch_queue_t = dispatch_queue_create("com.yourtion.SwiftFaceDetection.session_access_queue", DISPATCH_QUEUE_SERIAL)
     
     private var session:AVCaptureSession!
     private var backCameraDevice:AVCaptureDevice?

            possibleCameraInput = try AVCaptureDeviceInput(device: frontCameraDevice)
        } catch _ {
            possibleCameraInput = nil
        }
        if let backCameraInput = possibleCameraInput as? AVCaptureDeviceInput {
            if self.session.canAddInput(backCameraInput) {
                self.session.addInput(backCameraInput)
            }
        }
        previewLayer = AVCaptureVideoPreviewLayer(session: session)

        for metadataObject in metadataObjects as! [AVMetadataObject] {
            if metadataObject.type == AVMetadataObjectTypeFace {
                if let faceObject = metadataObject as? AVMetadataFaceObject {
                    let transformedMetadataObject = previewLayer.transformedMetadataObjectForMetadataObject(metadataObject)
                    let face:(id: Int, frame: CGRect) = (faceObject.faceID, transformedMetadataObject.bounds)
                    faces.append(face)
