Data syncing with DropBox API and iOS

Question

I have an iOS app which stores data in the local directory. I'd like to be able to sync this data between multiple devices running my app. Currently this is using core data, but I'd expect to have to change to some text-based file storage system to make syncing easier.

I was expecting the DropBox API would make this nice and easy, and that I could tell the API to simply sync the contents of my data folder on startup/save. However it seems the DropBox API is nothing more than a glorified way of uploading and downloading files.

Am I wrong on this assumption? Can the DropBox API actually make it easy to keep a folder full of text files in sync? If not, is there some other service or even advice you can give? Syncing is hard - I was hoping DropBox would make it easier.

Answer 1

Using /metadata, getting information about the contents of a folder couldn't be easier. All you need to do is check the modified date, and if it's different than yours locally, perform the appropriate action. It will also give you the metadata for any file contents, so you can pick out which files need to be uploaded / downloaded / added / removed as necessary.

Any more functionality than this would be very application-dependent; you can decide for yourself when and how you want to deal with differing files.

Dropbox API Documentation

Answer 2

Won't repeat since Andy has answered your question, thought you may also find this tutorial helpful:

http://www.nanaimostudio.com/blog/2011/1/20/how-to-synchronize-your-app-data-using-dropbox-api.html

Answer 3

Check out the new DropBox Sync API.

Answer 4

As ohho mentioned, there's the DropBox Sync API available now which I think will do what you mentioned (I haven't tried it personally, as I integrated support for Dropbox in my app using the earlier SDK, before this came along). This will probably suffice if you're just working with dropbox.

In my case I've been starting to add support for additional online storage ("Cloud") services to my app, and am finding that it's somewhat challenging to deal with the differences between them in how they handle various concepts like authentication, version, naming etc. For example Dropbox's API references files according to their path, whereas Box's API references files according to their file id (which has an associated path, but I believe remains the same if the file is moved). Then there's also all the issues of conflict resolution (aka merging) which come about when multiple clients try and sync conflicting changes to the server.

I've actually been recently considering starting an open source project to develop a library which can connect to all the major services, and provide an abstraction layer that papers over their differences, and also handles the syncing process for you. I've actually got some code already (which I haven't publicly released to date) but could use that to get the project started.

Would this be of use to you? Would you (or any others) be willing to participate in such an effort?

(note to mods: I realise this may be deviating somewhat off-topic - sorry about that. If you can recommend a more suitable forum to discuss this I'd be happy to take the conversation there).