Open Radar

 
Summary:
When using an iTunes Match library (with some songs downloaded on device), artworks are taking a lot of times to display, and some of them aren't available at a specific size (smaller ones it seems)
To avoid a lot of memory usage, I query a lot of thumbnail artworks from my library, and display bigger sizes later (when a track is playing for exemple).

Steps to Reproduce:
1. Open the project I attached
2. Run the App on an iOS device which has a fresh iTunes Match library on it
3. The app enumerates all your Albums and calls -representativeItem on each of them
4. The app displays 3 imageViews on screen with 3 different sizes (80, 120, 280)
5. Once the app founds out that an artwork couldn't be found for a specific size, but is available for the other sizes, it stops and pops an alert with more informations about the track MPMediaItemArtwork failed to retrieve the artwork at a specific size. 

(if no alert is being displayed at the end of albums enumeration, there is no error)


Expected Results:
MPMediaItemArtwork should provide an artwork for every sizes (if there's at least one-sized artwork, of course).
If no artwork available for a specific size, should return a greater or lower artwork instead.


Actual Results:
MPMediaItemArtwork does not return artworks for smaller sizes (sometimes)
My app failed at the first album. The 80*80 and 120*120 artworks couldn't be retrieved

Sample Project: http://cl.ly/0B1V3R3u1K39/ArtworkTesting.zip