ios - 如何使用 Swift 中的核心数据正确映射一对多关系？尝试期间出现 NSInvalidArgumentException 错误

Question

这是我的医学对象类和扩展:

import Foundation
import CoreData

class Medicine: NSManagedObject {

    @NSManaged var alarms: NSSet

}

-

import Foundation
import CoreData

extension Medicine {

@NSManaged var name: String?
@NSManaged var dosage: String?
@NSManaged var type: String?
@NSManaged var image: NSData?

func addAlarmObject(value:Alarm) {
    let items = self.mutableSetValueForKey("alarms") 
    items.addObject(value)
}

func removeDeleteObject(value:Alarm) {
    let items = self.mutableSetValueForKey("alarms")
    items.removeObject(value)
}

}

我的报警对象:

import Foundation
import CoreData

extension Alarm {

    @NSManaged var time: String?
    @NSManaged var weekdays: String?
    @NSManaged var isOwnedByMedicine: Medicine?

}

我的数据模型及其关系的屏幕截图:

最后，这是我要做的:

        let predicate = NSPredicate(format: "name == %@", currentMedicine)
        let fetchRequest = NSFetchRequest(entityName: "Medicine")
        fetchRequest.predicate = predicate
        var fetchedCurrentMedicine:Medicine!
        do {
            let fetchedMedicines = try managedContext.executeFetchRequest(fetchRequest) as! [Medicine]
            fetchedCurrentMedicine = fetchedMedicines.first
        } catch {

        }

        //add all the alarms to the Medicine class
        for alarmString in alarmList{
            let entity =  NSEntityDescription.entityForName("Alarm", inManagedObjectContext: managedContext)
            let alarm = NSManagedObject(entity: entity!, insertIntoManagedObjectContext: managedContext) as! Alarm
            alarm.setValue("test", forKey: "weekdays")
            alarm.setValue(String(alarmString), forKey: "time")
            fetchedCurrentMedicine.addAlarmObject(alarm)
        }
        do {
            try managedContext.save()
        } catch let error as NSError  {
            print("Could not save \(error), \(error.userInfo)")
        }

一直失败

fetchedCurrentMedicine.addAlarmObject(alarm)

我得到了错误:

“‘NSInvalidArgumentException’，原因:实体‘Medicine’的‘NSManagedObjects’不支持属性‘alarms’的-mutableSetValueForKey:”

知道我可能在哪里搞砸了或弄错了数据模型的模式吗？非常感谢。

Answer 1

在您的数据模型屏幕上，alarms Medicine 模型的关系是对一个。也许Alarm模型的medicines关系是to-many。
无论如何尝试在数据模型检查器中为 alarms 设置to-many 关系类型。