I stumbled across a paper about CloudKit. It's a good read if you are interested in the design considerations of Apple's cloud platform.
CloudKit: Structured Storage for Mobile Applications
http://www.vldb.org/pvldb/vol11/p540-shraer.pdf
CloudKit: Structured Storage for Mobile Applications
http://www.vldb.org/pvldb/vol11/p540-shraer.pdf