comments only

better method description
more comments
Again more comments
albumIdNumber
getAllAlbumsByArtist implemented
more album keys and an idea

Basically it would be possible to use custom NSDictionary subclasses to only provide valid methods for the returned JSON data (one subclass per API method). Behind the scenes the methods would reuse the generic key for whatever type the JSON data represents (album, artist, track, etc.). The risk of calling an "invalid" method on the JSON data would be impossible.
implemented Dictionary access to artist.getTopAlbums information
Adding NSDictionary subclasses for new architecture, amending API methods to conform.

implementation follows
Moving implementations from Category into own classes

needed to implement the constructor on the LFMDictionary to make a real subclass. Casting was (obviously) not enough.
Remove the NSDictionary category
Using Composition for the LFMDictionary's

Subclassing wasn't such a good idea
Renaming classes
Method names
Wrong object returned in success handler, plus more log statements