The iPhone OS completely removes the concept of a “file." It promotes apps to being the primary level of user interaction, and it stores related things inside databases that are content-specific. When you pick up your iPhone and want to view photos, you open the Photos app, which connects to the photos database and shows you all of your photos. When you want to listen to music, you open the iPod app, which connects to the music database. Everything on the iPhone is task-centric, not file-centric. The “file” part of completing tasks is completely insulated from the user.
-- Dustin Curtis, The Death of Files