I'm developing a Calendar app on iOS. In my application, I'm using EKEvent as event model. Since EKEvent is not a normal core data model, for example we should use eventWithEventStore: not insertNewObjectForEntityForName to create event, I'm not sure whether it's ok if I map some fields of EKEvent in RKObjectMapping.
You would need to do a bit of work to make it ok. In particular you would need to create your own data source for the mapping so it can create (or find the existing event to update) events and return them to be updated by the incoming data.