ios - Swift Combine 属性继承在 Xcode 11.4 beta 2/iOS 13.4 上抛出 'Fatal error: Call of deleted method'

Question

我正在尝试使用 Swift Combine 来获取属性的更改事件。

我有这个发布 isLogged 的类(class)属性(property)

class CurrentUser: Account {
    static let me = CurrentUser() //Singleton 

    @Published var isLogged: Bool = false

}

继承自发布 profileImageVersion 的其他类属性(property)

class Account {

    @Published var profileImageVersion: String?

    init(){
       self.profileImageVersion = ""
    }
}

我正在尝试订阅已发布的继承 profileImageVersion像这样的属性(property)没有成功!

// Subscribe to account image changes
userImageChangedSubscriber = CurrentUser.me.$profileImageVersion.receive(on: DispatchQueue.main).sink(receiveValue: { (imageVersion) in           
       ...
    }
})

错误是 Fatal error: Call of deleted method
另一方面，如果我订阅 isLogged属性(property)，一切正常...

// Subscribe to logged changes
userLoggedSubscriber = CurrentUser.me.$isLogged.receive(on: DispatchQueue.main).sink(receiveValue: { (logged) in
   ...
})

此错误仅在 Xcode 11.4 beta 2/iOS 13.4 上引发。
使用 Xcode 11.3.1/13.3 一切正常!

Answer 1

我遇到了同样的崩溃，作为临时解决方法，我发现将所有已发布的属性移动到您正在使用的具体类将解决问题。我有这样的设置:

class EpisodesViewModel {
  @Published var episodes: [Episode]

  init(fetchRequest: NSFetchRequest<Episode>, context: NSManagedObjectContext? = nil) throws {
    ...
  }
  ...
}

使用这个模型的子类，它只是给出了一个获取请求:

final class LatestEpisodesViewModel: EpisodesViewModel {
    init() throws {
        try super.init(fetchRequest: Episode.latestFetchRequest())
    }
}

通过将我的设置更改为此，我能够修复崩溃:

class EpisodesViewModel {
    var fetchedEpisodes: [Episode]

    init(fetchRequest: NSFetchRequest<Episode>, context: NSManagedObjectContext? = nil) throws {
        ...
    }
    ...
}

final class LatestEpisodesViewModel: EpisodesViewModel {

    @Published var episodes: [Episode] = []

    override var fetchedEpisodes: [Episode] {
        didSet {
            episodes = fetchedEpisodes
        }
    }

    init() throws {
        try super.init(fetchRequest: Episode.latestFetchRequest())
    }
}

对我来说，这当然像是一个 Apple 错误，但这同时也让我解决了这个问题。