ios - 为什么搜索模型文件的路径时扩展名是 "momd"而不是 "xcdatamodel"

Question

我使用 Core Data 创建了一个主从应用程序。并且有一个简单的代码获取模型文件的路径:

NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"Model" withExtension:@"momd"];

我不知道为什么扩展名不是“xcdatamodel”而是“momd”。

有人知道答案吗？

Answer 1

mom 和momd 文件是xcdatamodel 和xcdatamodeld 文件的编译版本。

关于编译过程如何工作的信息here (第 31 页)。引用文档:

A data model is a deployment resource. In addition to details of the entities and properties in the model, a model you create in Xcode contains information about the diagram—its layout, colors of elements, and so on. This latter information is not needed at runtime. The model file is compiled using the model compiler, momc, to remove the extraneous information and make runtime loading of the resource as efficient as possible.