使用CATiledLayer绘制Core Data实体信息时如何正确处理线程

I'm contemplating how to offload the drawing of a very large Core Data tree structure to CATiledLayer. CATiledLayer seems to be awesome because it performs drawing on a background thread and then fades in tiles whenever they're drawn. However, because the information of the drawing comes from a Core Data context that is by design not thread safe, I'm running into race condition issues where the drawing code needs to access the CD context.I'm contemplating how to offload the drawing of