During last year's WWDC, Apple introduced CloudKit, a brand new framework that directly interacts with Apple's iCloud servers. The framework is comparable to a number of PaaS (Platform as a Service) solutions, such as Parse. Like Parse, Apple provides a flexible API and a dashboard that offers developers a peek into the data stored on Apple's iCloud servers. In this series, you will learn about the CloudKit framework and infrastructure by building a shopping list application.
Source files for the Tuts+ tutorial: Building a Shopping List Application With CloudKit: Introduction
Read this tutorial on Tuts+