问题描述
在添加Core Data相关代码后，运行Xcode项目提示如下报错：
warning: Multiple NSEntityDescriptions claim the NSManagedObject subclass 'ERdepot.CryptoCurrency' so +entity is unable to disambiguate.
CoreData: warning: Multiple NSEntityDescriptions claim the NSManagedObject subclass 'ERdepot.CryptoCurrency' so +entity is unable to disambiguate.
...
error: +[ERdepot.CryptoCurrency entity] Failed to find a unique match for an NSEntityDescription to a managed object subclass
CoreData: error: +[ERdepot.CryptoCurrency entity] Failed to find a unique match for an NSEntityDescription to a managed object subclass
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'executeFetchRequest:error: A fetch request must have an entity.'
*** First throw call stack:
(0x1a7c9cf20 0x19fb432b8 0x1afd97c94 0x1afe3d9f4 0x1afd8dfe8 0x1afe04124 0x1abe60294 0x1abe0c860 0x1abe1861c 0x104951204 0x104951734 0x1cb443154)
libc++abi: terminating due to uncaught exception of type NSException根据报错的信息，了解到有多个 CryptoCurrency 实体在 Core Data 的模型中指向了同一个 NSManagedObject 子类 ERdepot.CryptoCurrency，导致系统不知道该用哪个。最终导致 @FetchRequest 无法解析出该用哪个实体，结果抛出异常崩溃。
问题原因
当我根据报错信息了解到是@FetchRequest的原因后，我将刚刚添加的@FetchRequest代码隐藏后，报错消失并且可以安装、运行应用。
// 使用 @FetchRequest 获取数据
// @FetchRequest(
// sortDescriptors: [NSSortDescriptor(keyPath: \CryptoCurrency.marketCapRank, ascending: true)],
// animation: .default)
// private var cryptoCurrencys: FetchedResults<CryptoCurrency>我在对比的过程中，发现我的这个@FetchRequest的代码写法有问题，与我前面正常的@FetchRequest代码不同。
@FetchRequest(
fetchRequest: {
let request = NSFetchRequest<CryptoCurrency>(entityName: "CryptoCurrency")
request.sortDescriptors = [NSSortDescriptor(keyPath: \CryptoCurrency.marketCapRank, ascending: true)]
return request
}()
) var cryptoCurrencys: FetchedResults<CryptoCurrency>之前正常的@FetchRequest是这样的。
当我将 @FetchRequest 修改为之前正常的样式时，问题得到解决。
总结
没有想到这个问题竟然是@FetchRequest造成的，我尝试清理构建文件夹和DerivedData文件夹，仍然不起作用。
在将@FetchRequest修改为之前的样式后，问题猜得到解决。
这个报错的@FetchRequest代码还是从我之前学习Core Data的文章中复制过来的，真是误人子弟啊，现在已经将Core Data文章中的这个代码修复成功。
相关文章
Apple Core Data持久化框架：https://fangjunyu.com/2025/03/30/apple-coredata%e6%8c%81%e4%b9%85%e5%8c%96%e6%a1%86%e6%9e%b6/
