When I started to finalize the features for the WhoNote agent app I knew I wanted to give users the ability to choose multiple music sources. Out of the gate the first two choices I wanted to support were iTunes and Spotify. Arguably the most common sources.
Coming from iOS development I had the naive assumption that there would an Cocoa equivelant of the MediaPlayer Framework. There isn’t. I became one sad panda. I saw quite a number of people “get around the problem” by writing AppleScripts and running them from the command line or including the AppleScript(s) in their apps and calling them directly. That would have worked, but there had a be a native way of interacting with iTunes. My use case is quite simple: Listen for track change notifications and upload meta data.
RTFM
When in doubt one should read the manual. Apple has provided an excellent example of how to natively interact with iTunes. Though the subject of ScriptBridging is much broader than just iTunes, the example couldn’t be better.
Needless to say incorporating iTunes support was a breeze.
Playtime with Spotify
Now that I had a native methodolgy to go by adding in Spotify support was just as easy. First I had to generate the header file:
sdef /Applications/Spotify.app | sdp -fh --basename SpotifyClient
Note
I did get the following error message when I ran the above command:
sdp: warning: class “SpotifyClientApplication” redeclared; use instead.
I’m not sure yet if this is bug in the sdp or if I didn’t pass in a correct param, but basically in your generated header file you’ll have a class forwarding delcaration twice.
@class SpotifyClientApplication, SpotifyClientTrack, SpotifyClientApplication;
Just open the file, remove one and you are good to go.
Being a Good Listener
Though I could interact with both services, the functionality that I needed was to listen for state and song changes. Both services “broadcast” this information through NSDistributedNotificationCenter.
iTunes Notification
com.apple.iTunes.playerInfo
2013-04-08 11:12:13.652 WhoNoteMac[7939:303] notification payload: {
Album = "Collide With the Sky";
"Album Artist" = "Pierce the Veil";
"Album Rating" = 0;
"Album Rating Computed" = 1;
Artist = "Pierce the Veil";
"Artwork Count" = 1;
"Disc Count" = 1;
"Disc Number" = 1;
Genre = Alternative;
"Library PersistentID" = 162261630986489880;
Location = "file://localhost/Users/cwiles/Music/iTunes/iTunes%20Media/Music/Pierce%20the%20Veil/Collide%20With%20the%20Sky/07%20Tangled%20In%20the%20Great%20Escape%20(feat.%20Jason%20Butler).m4a";
Name = "Tangled In the Great Escape (feat. Jason Butler)";
PersistentID = "-7678479651277138133";
"Play Count" = 1;
"Play Date" = "2013-04-08 14:24:50 +0000";
"Player State" = Playing;
"Playlist PersistentID" = 1335587615931680054;
"Rating Computed" = 1;
"Skip Count" = 0;
"Store URL" = "itms://itunes.com/album?p=536038964&i=536039373";
"Total Time" = 356893;
"Track Count" = 13;
"Track Number" = 7;
Year = 2012;
}
Spotify Notification
com.spotify.client.PlaybackStateChanged
2013-04-08 11:18:52.679 WhoNoteMac[8053:303] notification payload: {
Album = "In Search Of Solid Ground";
"Album Artist" = Saosin;
Artist = Saosin;
"Disc Number" = 1;
Duration = 215;
"Has Artwork" = 1;
Location = "/Users/cwiles/Music/iTunes/iTunes Media/Music/Saosin/In Search Of Solid Ground/08 The Worst Of Me.m4a";
Name = "The Worst Of Me";
"Play Count" = 0;
"Playback Position" = 0;
"Player State" = Playing;
Popularity = 38;
Starred = 0;
"Track ID" = "spotify:track:1wiIhmcIU1hJWqEKhcaXcp";
"Track Number" = 8;
}
Finally with all the pieces in places I was able to get all the meta information I need to send to the WhoNote backend. While I do wish there was an official Cocoa framework to interact with iTunes; utilizing ScriptBridging does provide a blessed mechanism for interacting with other installed applications.