swift – CoreData使用nil属性创建和保存额外的实体

我创建一个联系人保存,然后创建一个位置并保存,然后将保存的位置分配给联系人.代码如下：

@IBAction func saveLocation(_ sender: AnyObject) {
    let processName = ProcessInfo.processInfo.globallyUniqueString

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

    do {

        let fetchRequest: NSFetchRequest<Contact> = Contact.fetchRequest()
        fetchRequest.predicate = NSPredicate(format: "uniqueId == %@",contactIdentifierString)
        let fetchedResults = try context.fetch(fetchRequest)
        if let aContact = fetchedResults.first {

            // set location data
            location.uniqueId = processName
            location.locationName = locationNameTextField.text
            location.city = self.city
            location.state = self.state
            location.street = self.street
            location.zip = self.zip
            location.country = self.country


            // save data
            (UIApplication.shared.delegate as! AppDelegate).saveContext()
            location.contact = aContact
            myDelegate?.userSelectedContact(contactIdentifier: contactIdentifierString,locationIdentifier: processName)

        }
    }
    catch {
        print ("fetch task failed",error)
    }




    // Check results
    do {

        let fetchRequest: NSFetchRequest<Location> = Location.fetchRequest()
        fetchRequest.predicate = NSPredicate(format: "uniqueId == %@",processName)
        let fetchedResults = try context.fetch(fetchRequest)
        if let aLocation = fetchedResults.first {
            print("+++++==========++++++++++")
            print("Location.Contact:  (aLocation.contact)")
            print("+++++==========++++++++++")
        }
    }
    catch {
        print ("location fetch failed")
    }

    self.navigationController!.popViewController(animated: true)
}

我只添加了一个位置,但是当我打印联系人实体时,我看到分配了两个位置,如下所示.

此外,位置实体之一具有正确的分配属性的值,其中另一个位置实体具有所有零值.
这搞砸了我的计划.当我在循环中查看位置实体属性以删除它们时,我现在看到三个位置实体


输出：
要删除的地点数量:: 3
在我的代码的后半部分,当我尝试检索值时,它崩溃,因为两个额外的Location实体的所有属性都是nil.
我的问题：
因为我只添加了一个Location实体,所以应该只有一个Location实体,而且应该是唯一一个链接到Contact的实体.它显示了分配给Contact的两个Locations,然后当我得到计数??时,我有三个Locations.看起来具有nil属性的Location实体会自行添加.
我很迷惑.有人可以帮忙吗？
Location.Contact:  Optional(<rg2nrg.Contact: 0x6000002c73f0> (entity: Contact; id: 0xd000000000240000 <x-coredata://7D46FA65-2590-409D-89E7-995F64F07483/Contact/p9> ; data: {
email = vmail;
firstName = vr;
imageName = <89504e47 0d0a1a0a 0000000d 49484452 0000012c 0000012c 08
 @IBAction func saveLocation(_ sender: AnyObject) {
    let processName = ProcessInfo.processInfo.globallyUniqueString

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

    do {

        let fetchRequest: NSFetchRequest<Contact> = Contact.fetchRequest()
        fetchRequest.predicate = NSPredicate(format: "uniqueId == %@",processName)
        let fetchedResults = try context.fetch(fetchRequest)
        if let aLocation = fetchedResults.first {
            print("+++++==========++++++++++")
            print("Location.Contact:  (aLocation.contact)")
            print("+++++==========++++++++++")
        }
    }
    catch {
        print ("location fetch failed")
    }

    self.navigationController!.popViewController(animated: true)
}
@IBAction func saveLocation(_ sender: AnyObject) {
    let processName = ProcessInfo.processInfo.globallyUniqueString

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

    do {

        let fetchRequest: NSFetchRequest<Contact> = Contact.fetchRequest()
        fetchRequest.predicate = NSPredicate(format: "uniqueId == %@",processName)
        let fetchedResults = try context.fetch(fetchRequest)
        if let aLocation = fetchedResults.first {
            print("+++++==========++++++++++")
            print("Location.Contact:  (aLocation.contact)")
            print("+++++==========++++++++++")
        }
    }
    catch {
        print ("location fetch failed")
    }

    self.navigationController!.popViewController(animated: true)
}0 00797d8e 75000000 01735247 4200aece 1ce90000 0009>;
 lastName = r;
 locations = (
 "0xd000000001780002 <x-coredata://7D46FA65-2590-409D-89E7-995F64F07483/Location/p94>",
 "0xd000000001740002 <x-coredata://7D46FA65-2590-409D-89E7-995F64F07483/Location/p93>"
 );
 phone = 22;
 providerName = tara;
 screenName = vr;
 uniqueId = "7B17C228-50A6-4309-BD0D-CBCD8E8FAEA1-1106-00000128477D4DB1";
 userType = Household;
 }))
func deleteLocations() {
    var fetchedResults: [Location] = []

    let contextLocation = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
    do {

        fetchedResults = try contextLocation.fetch(Location.fetchRequest())
        print("number of locations to be deleted:: (fetchedResults.count) ")

        if fetchedResults.count > 0 {

            for location in fetchedResults{
                print(location.locationName)
                contextLocation.delete(location)
                try contextLocation.save()

                print(location.locationName)
            }
        }
    } catch {
        print ("fetch contact failed")
    }

}