我一直在研究一种方法，在多个设备(如iPad或Mac)之间同步存储在iPhone应用程序中的核心数据。在iOS上，用于core data的同步框架并不多(如果有的话)。然而，我一直在思考以下概念:

A change is made to the local core data store, and the change is saved. (a) If the device is online, it tries to send the changeset to the server, including the device ID of the device which sent the changeset. (b) If the changeset does not reach the server, or if the device is not online, the app will add the change set to a queue to send when it does come online. The server, sitting in the cloud, merges the specific change sets it receives with its master database. After a change set (or a queue of change sets) is merged on the cloud server, the server pushes all of those change sets to the other devices registered with the server using some sort of polling system. (I thought to use Apple's Push services, but apparently according to the comments this is not a workable system.)

有什么特别的需要我考虑的吗?我已经研究了REST框架，如ObjectiveResource、Core Resource和RestfulCoreData。当然，这些都是与Ruby on Rails一起工作的，我并不依赖于Ruby on Rails，但这是一个起点。我的解决方案的主要要求是:

任何更改都应该在后台发送，而不需要暂停主线程。 它应该使用尽可能少的带宽。

我想过一些挑战:

Making sure that the object IDs for the different data stores on different devices are attached on the server. That is to say, I will have a table of object IDs and device IDs, which are tied via a reference to the object stored in the database. I will have a record (DatabaseId [unique to this table], ObjectId [unique to the item in the whole database], Datafield1, Datafield2), the ObjectId field will reference another table, AllObjects: (ObjectId, DeviceId, DeviceObjectId). Then, when the device pushes up a change set, it will pass along the device Id and the objectId from the core data object in the local data store. Then my cloud server will check against the objectId and device Id in the AllObjects table, and find the record to change in the initial table. All changes should be timestamped, so that they can be merged. The device will have to poll the server, without using up too much battery. The local devices will also need to update anything held in memory if/when changes are received from the server.

我还遗漏了什么吗?我应该考虑什么样的框架来实现这一点?