User Profile

We have an iOS application that is using a third party c library, which uses UNIX domain sockets to manage and save content to the device. We have found that this is possible by using Application Groups. We are now interested in using iCloud to sync the data between multiple devices. However, I've been unable to find any documentation on how to do this or if it's possible just using App groups. I've built a simple prototype, but I have had no success syncing App Group files through iCloud. Is this possible? If so, please post a link to documentation or an example of this being done.