@interface _DKNowPlayingMetadataKey : NSObject

+ (id)iTunesSubscriptionIdentifier;
+ (id)isAirPlayVideo;
+ (id)playing;
+ (id)iTunesStoreIdentifier;
+ (id)outputDeviceIDs;
+ (id)genre;
+ (id)identifier;
+ (id)album;
+ (id)elapsed;
+ (id)artist;
+ (id)mediaType;
+ (id)title;
+ (id)duration;

@end