                                                     loaded: availableDuration,
                                                     outOf: totalDuration)
                     }
-                case KPlaybackBufferEmptyKey:
+                case kPlaybackBufferEmptyKey:
                     if playerItem.playbackBufferEmpty {
                         self.player.changeState(.Buffering)
                     }

        self.avPlayerItem?.removeObserver(self, forKeyPath: kStatusKey)
        self.avPlayerItem?.removeObserver(self, forKeyPath: kLoadedTimeRangesKey)
        self.avPlayerItem?.removeObserver(self, forKeyPath: kPlaybackLikelyToKeepUp)
        self.avPlayerItem?.removeObserver(self, forKeyPath: KPlaybackBufferEmptyKey)
        self.avPlayerItem = nil
        self.mediaResourceLoader?.session.invalidateAndCancel()
    }

            context: &myContext
        )
        self.avPlayerItem!.addObserver(self,
                                       forKeyPath: kPlaybackBufferEmptyKey,
                                       options: NSKeyValueObservingOptions.New,
                                       context: &myContext)
        self.avPlayerItem!.addObserver(self,
