Mendix does not have generic support for offline (mobile) client operations. I have heard of at least one partner who has created a custom native mobile application and synchronizes it using webservices. If this is what you want, that sounds like the way to go.
If you install a Mendix server on the client and build the synchronisation within Mendix with Web Services you could accomplish this.
However I don't know if an iPad supports java. Most other mobile's do, but please test it first.