Cloud sync is a feature that every iOS app is expected to have, and yet is notoriously difficult to implement in a robust way. It usually demands a small team of iOS and web developers working together, not to mention the deep pockets needed to pay for cloud services and storage.

The open source Ensembles framework has changed that. You can now build sync into an iOS app using Core Data in a matter of hours, and take your pick of cloud services, including free services like Dropbox and iCloud.

This book introduces you to the goals of the project, and how to install and integrate it in your app. It also covers advanced topics like conflict resolution, and the pitfalls to beware of when your app supports sync.