ios - (Swift 3)父子上下文崩溃核心数据(libc++abi.dylib : terminating with uncaught exception of type NSException (Recorded Frame) )

Question

我正在尝试将消息保存在后台队列中，并通过使用两个上下文(父项和子项)将它们推送到主队列。但我的应用程序不断崩溃。我使用了 apples docs，不知道为什么它不起作用......

Core Data, Multithreading, and the Main Thread

这是我的代码:

let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext

let privateMOC = NSManagedObjectContext(concurrencyType: .privateQueueConcurrencyType)


let doubletimestamp = Double(timestamp)
    let date = Date(timeIntervalSinceReferenceDate: (doubletimestamp))
    let status = "..."

    let message = NSEntityDescription.insertNewObject(forEntityName: "Mesages", into: self.privateMOC) as! Mesages
    message.text = text
    message.timestamp = date as NSDate        

    do {
        try self.privateMOC.save()
        self.inputToolbar.toggleSendButtonEnabled()

        self.context.performAndWait {

            do {
                try self.context.save()
            } catch {
                fatalError("Failure to save context: \(error)")
            }

        }

    }catch let err {
        print(err)
    }

    }

这也是我的堆栈跟踪:

Answer 1

好吧，你有两个问题。

首先是你没有设置父上下文。如果您不这样做，则不会将任何内容传播到您的主要托管上下文

第二个是您没有在它自己的 block 中更改私有(private)托管上下文。就像您的正常托管上下文需要运行(您已经完成)一样，私有(private)上下文也需要执行相同的操作。

所以完成的代码应该是这样的:-

let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext

let privateMOC = NSManagedObjectContext(concurrencyType: .privateQueueConcurrencyType)

private.parentContext = context

let doubletimestamp = Double(timestamp)
let date = Date(timeIntervalSinceReferenceDate: (doubletimestamp))
let status = "..."

privateMOC.performBlock {

    let message = NSEntityDescription.insertNewObject(forEntityName: "Mesages", into: self.privateMOC) as! Mesages
    message.text = text
    message.timestamp = date as NSDate        

    do {
        try self.privateMOC.save()
        self.inputToolbar.toggleSendButtonEnabled()

        self.context.performAndWait {

            do {
                try self.context.save()
            } catch {
                fatalError("Failure to save context: \(error)")
            }

        }

    }catch let err {
        print(err)
    }

    }
}