The app is a tabbed app (have tab in the bottom area in wich you can switch view)
The first tab :
The home screen of the app is the user library,
in this screen he see the mp3 that he marked as favorites (or downloaded)
The second tab :
The second screen is the online library,
these are listed the categories, when the user click on a category the app go to another where are listed all the mp3 in that category
When the user click on a mp3 the app goes to the third tab (playing screen)
in this view the user can pause/play the song, change volume and seek the song to other points.
There is a button to add the song to the favourites