iOS核心数据未执行轻量级迁移

Question

I have a model with two entities, let's say A and B . The model is loaded from sqlite file downloaded from the internet (conforming to Core Data's sqlite format; ie Tables and columns beginning with 'Z').

I added a new version for my model; introducing a non-optional integer attribute with default value of zero to the entity B . For some reason, whenever I query that entity, I get nil result, and an error object of no such column ZVERSION ( version is the new attribute name), even if I'm not using version in my query.

What probably can be wrong?

Answer 1

You can have a attributes named 'version' - it is reserved. From apple's docs:

Note that a property name cannot be the same as any no-parameter method name of NSObject or NSManagedObject. For example, you cannot give a property the name "description". There are hundreds of methods on NSObject which may conflict with property names—and this list can grow without warning from frameworks or other libraries. You should avoid very general words (like "font”, and “color”) and words or phrases which overlap with Cocoa paradigms (such as “isEditing” and “objectSpecifier”).

(source: https://developer.apple.com/reference/coredata/nspropertydescription )

'version' is a class method of NSObject used in archiving: https://developer.apple.com/reference/objectivec/nsobject/1415151-version

Also creating an SQL file outside of core data and importing it is not supported. Apple does not publish it's sqlite format and you may not be conforming it. Perhaps Apple has some ZVERION column that you are unaware of.