ios - 是否没有必要在 Swift 3 中子类化 NSManagedObject？

Question

我以前知道您必须“编辑器”>“创建 NSManagedObject 子类”才能在您的类中引用核心数据的实体名称。但是，在创建这些自动子类后，我遇到了几个错误。

我的项目在没有这些子类文件的情况下运行良好，那么 Swift 3 是否不再需要子类来引用实体？

Answer 1

在 Swift 3 中，您不需要手动为 NSManagedObject 创建子类。

默认情况下，它们是自动创建的。但是，如果您想要手动创建文件，请在您的 testCD.xcdatamodeld 的实用程序区域中将 Codegen 设置为 Manual/None。

来自 Apple 的 What's new in Core Data :

Xcode automatic subclass generation

Xcode now supports automatic generation of NSManagedObject subclasses in the modeling tool. In the entity inspector:

• Manual/None is the default, and previous behavior; in this case youshould implement your own subclass or use NSManagedObject.
• Category/Extension generates a class extension in a file named likeClassName+CoreDataGeneratedProperties. You need to declare/implementthe main class (if in Obj-C, via a header the extension can importnamed ClassName.h).
• Class Definition generates subclass files named like ClassName+CoreDataClass as well as the files generated for Category/Extension.

The generated files are placed in DerivedData and rebuilt on the first build after the model is saved. They are also indexed by Xcode, so command-clicking on references and fast-opening by filename works.