访问最终类的@NSManaged属性时出现Swift链接器错误 [英] Swift linker error when accessing @NSManaged properties of a final class

问题描述

我在一个较大的项目中遇到了问题，并将其归结为这个简单的代码.出于演示目的，我在Model.swift文件中创建了一个新的Swift项目，其中包含以下内容:

I'm having issues in a larger project, and boiled it down to this simple code. For demo purposes, I have created a new Swift project with the following in a Model.swift file:

import Foundation
import CoreData

class A: NSManagedObject {
    @NSManaged var foo: String
}

final class B: A {
    @NSManaged var bar: String
}

func testB(obj: B) -> String {
    return "\(obj.foo) \(obj.bar)"
}

这可以编译，但是链接器抱怨访问 bar :

This compiles, but the linker complains about accessing bar:

Undefined symbols for architecture armv7:
  "__TFC21TestFinalManagedClass1Bg3barSS", referenced from:
      __TF21TestFinalManagedClass5testBFCS_1BSS in Model.o
ld: symbol(s) not found for architecture armv7
clang: error: linker command failed with exit code 1 (use -v to see invocation)

@NSManaged var 在 final类中的组合似乎是导致错误的原因.(包含了来自 A 的类继承关系，以证明 foo 属性可在类型为 B 的对象上访问，但不能访问bar 属性.)

The combination of an @NSManaged var in a final class seems to be what causes the error. (The class inheritance from A is included to demonstrate that the foo property is accessible on an object of type B, but not the bar property.)

我正在使用Xcode版本6.1(6A1052d).

I am using Xcode Version 6.1 (6A1052d).

文档中是否存在一些关于将 NSManagedObject 子类标记为最终规则的规则?还是这仅仅是编译器/链接器中的错误?

Is there some rule hidden in the documentation about marking an NSManagedObject subclass as final? Or is this just a bug in the compiler/linker?

推荐答案

此问题已在Xcode 6.3 beta中得到解决.

This issue has been resolved in Xcode 6.3 beta.

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