将数据保存到核心数据中会迅速覆盖所有记录

Question

我有一个显示动物列表的表格视图，在每个单元格（或动物）上轻按，可导航到动物的详细信息，并具有保存按钮 每当我使用核心数据保存信息时，核心数据中的所有记录都会被最近更新的数据覆盖。 我不确定这可能是什么原因。该代码的参考来自本帖子： Swift 3 IOS 9 And IOS 10 Core Data

下面是代码

class CoreDataStack {

    static var applicationDocumentsDirectory: URL = {

        let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
        return urls[urls.count-1]
    }()

    static var managedObjectModel: NSManagedObjectModel = {
        // The managed object model for the application. This property is not optional. It is a fatal error for the application not to be able to find and load its model.
        let modelURL = Bundle(for: CoreDataStack.self).url(forResource: "DatabaseTest", withExtension: "momd")! // type your database name here..
        return NSManagedObjectModel(contentsOf: modelURL)!
    }()

    static var persistentStoreCoordinator: NSPersistentStoreCoordinator = {
        // The persistent store coordinator for the application. This implementation creates and returns a coordinator, having added the store for the application to it. This property is optional since there are legitimate error conditions that could cause the creation of the store to fail.
        // Create the coordinator and store
        let coordinator = NSPersistentStoreCoordinator(managedObjectModel: managedObjectModel)
        let url = applicationDocumentsDirectory.appendingPathComponent("DatabaseTest.sqlite") // type your database name here...
        var failureReason = "There was an error creating or loading the application's saved data."
        let options = [NSMigratePersistentStoresAutomaticallyOption: NSNumber(value: true as Bool), NSInferMappingModelAutomaticallyOption: NSNumber(value: true as Bool)]
        do {
            try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url, options: options)
        } catch {
            // Report any error we got.
            var dict = [String: AnyObject]()
            dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data" as AnyObject
            dict[NSLocalizedFailureReasonErrorKey] = failureReason as AnyObject

            dict[NSUnderlyingErrorKey] = error as NSError
            let wrappedError = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
            // Replace this with code to handle the error appropriately.
            // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
            NSLog("Unresolved error \(wrappedError), \(wrappedError.userInfo)")
            abort()
        }

        return coordinator
    }()

    static var managedObjectContext: NSManagedObjectContext = {
        // Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.) This property is optional since there are legitimate error conditions that could cause the creation of the context to fail.
        let coordinator = persistentStoreCoordinator
        var managedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
        managedObjectContext.persistentStoreCoordinator = coordinator
        return managedObjectContext
    }()

static func getEntity<T: NSManagedObject>() -> T {
    if #available(iOS 10, *) {
        let obj = T(context: CoreDataStack.context)
        return obj
    } else {
        guard let entityDescription = NSEntityDescription.entity(forEntityName: NSStringFromClass(T.self), in: CoreDataStack.context) else {
            fatalError("Core Data entity name doesn't match.")
        }
        let obj = T(entity: entityDescription, insertInto: CoreDataStack.context)
        return obj
    }
}

    // MARK: - Core Data Saving support

    static func saveContext () {
        if managedObjectContext.hasChanges {
            do {
                try managedObjectContext.save()
            } catch {
                // Replace this implementation with code to handle the error appropriately.
                // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
                let nserror = error as NSError
                NSLog("Unresolved error \(nserror), \(nserror.userInfo)")
                abort()
            }
        }
    }

}

在点击保存按钮时，我将此代码称为

   let animalObj: animalTable = CoreDataStack.getEntity()

        animalObj.Name = animalModel.Name
        animalObj.Type = animalModel.Type

    CoreDataStack.saveContext()

不确定，在保存最后数据的情况下覆盖核心数据中的所有数据的问题在哪里。