I'm using Simperium to sync instances of my app's data between each other. I went with this over iCloud because I've heard iCloud has a lot of issues with Core Data and as a novice to iOS, I believe Apple makes you pay to use their services (in a form of developer membership). Since my project is academic, there isn't a need for this.
I've set up Simperium to sync data from my app to their servers, and it's syncing well, but it seems it doesn't have support for binary data. My application syncs items and wishlists, and an item always has an image associated to it. The thumbnail I store in Core Data, since it's small (75x75), and the large image using NSFileManager. None of these sync.
Is it possible to enable sync for binary data and/or images stored in the app's sandboxed documents folder using Simperium? I've heard it's experimental, but if it works decently, I'll be glad to enable it. If not, are there any other frameworks that use sync and don't require iCloud to sync Core Data with binary data?
Syncing binary data isn't yet officially supported by Simperium, but you can track this GitHub issue for it. At the moment it won't work experimentally, either.
One strategy that some other developers are using is to sync filenames using Simperium (since they're just strings), and then deal with the corresponding data files on your own, either manually or with the help of another system like Amazon S3.