Topic: Syncing Data

We have an app that is heavy on user inputted data on the iPhone. With the coming of the iPad, we are thinking we need to support data sync between the iPhone and the iPad so that the user can input/view data that they entered in either device on the other.

So the easiest way is to have all of the info on the cloud and have the iPhone/iPad simply be a "viewing" mechanism. But the problem is, users use our app without needing wifi or 3g. So we need to store a copy on the cloud, in the iPhone, and in the iPad.

Any ideas on how to do this? How complicated this is? What logic we need in it? A way to do it that's as solid and free from wrong data sync as possible? Any things to watch out for?

Re: Syncing Data

I had a similar issue with one of my apps although our design was not to capture user entry on the iphone side but to provide an offline method so the app would work when in airplane mode (no Wifi/3G).  We ended up building a mechanism with XML to handle which worked but wasn't too pretty.  We basically stored a revision system on the phone and the server, when there was variations we would push up/down the data.  We did also look into to managing a change system with the data on the phone in sqlite however that seemed pretty complex.  I'll be interested to hear what others recommend.

Re: Syncing Data

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Re: Syncing Data


The best solution I have found for Objective-C integration with rails is: However, offline support is not included in the main trunk. Might be able to find a good branch though or write your own. At least it offers a good starting point. Just a note, that this adds lots of complexity. It might be worth re-assessing whether it is offline support is 'required'. Also, it might be worth checking out JQTouch ( and

Re: Syncing Data

As far as I know Apple just released Apple iCloud, it's supposed to do exactly what you need. We're using an enterprise private cloud for this sort of things and the formula works pretty well for us. There are several interesting resources here as well, resources that I wasn't aware of so far...