iPhone and iPad App 24-Hour Trainer

Chapter 25

Introduction to iCloud Storage

iCloud Storage is a set of classes and services that enable you to share data between instances of your application running across different devices. In this lesson you learn to use the iCloud Storage APIs in your apps.

Basic Concepts

Apple’s iCloud is a service that allows applications to synchronize data across devices. Your data is stored across a set of servers maintained by Apple and is made available to copies of your app across all iCloud-compatible devices. Changes made to this data by one instance of your application are automatically propagated to other instances.

From a developer’s perspective, you need to use Apple’s iCloud Storage APIs to interact with the iCloud service. These APIs enable you to store both documents and small amounts of key-value data.

This lesson does not cover key-value data storage. For more information on storing key-value data with iCloud, refer to the iCloud Storage section of the “iOS App Programming Guide,” available at http://developer.apple.com/library/ios/#documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/iCloud/iCloud.html#//apple_ref/doc/uid/TP40007072-CH5-SW1.

iCloud applications cannot be tested on the iOS Simulator, and to make the most of this lesson you should ideally have two iOS devices to test on. As of now, the iCloud Storage APIs are available to both iOS 5 and MacOS X developers. ...