ios - swift:检查核心数据中的记录

Question

有没有办法从 Xcode 检查核心数据？

我创建了两个函数(写入数据库，从数据库读取)，它们不会失败，但读取在应该返回写入数据时返回空数组。

功能:

func writeData () {
        appDel = UIApplication.sharedApplication().delegate as! AppDelegate
    context = appDel.managedObjectContext

        let newRecord = NSEntityDescription.insertNewObjectForEntityForName("CountryList", inManagedObjectContext: context) as NSManagedObject

        let timestamp = NSDate()

        for geo in geoArray {

        //geoArray - array of dictionaries ([CountryName: "Lithuania", TelCode: 370],[CountryName: "Belarus", TelCode: 375],[CountryName: "Latvia", TelCode: 371])             
        //geo - Dictionary of tipe <String: AnyObject>
        // CoreData: countryName type is String

        newRecord.setValue(timestamp, forKey: "dateUploaded")
        newRecord.setValue(String(geo["CountryName"]!), forKey: "countryName")

            do {
                try context.save()
                print("Saved successfully")
            } catch _ {
                print("there was issue saving data!")
            }  

          }


        } 







  func loadData(country: String) {
        appDel = UIApplication.sharedApplication().delegate as! AppDelegate
        context = appDel.managedObjectContext


        results = [AnyObject]()

        let request = NSFetchRequest(entityName: "CountryList")
        request.resultType = NSFetchRequestResultType.DictionaryResultType

        request.predicate = NSPredicate(format: "countryName = %@", country)



        let sort1 = NSSortDescriptor(key: "dateUploaded", ascending: true)

        request.sortDescriptors = [sort1]

        do {
            results = try context.executeFetchRequest(request)
            print(results!)

        } catch _ {
            print ("error trying to fetch!")
        }
    }

我想从 Xcode 检查我的 CoreData 实体中是否有任何记录。那可能吗？

谢谢

Answer 1

您实际上是在循环内更改相同的核心数据对象。因此，最终在循环结束时，您将只剩下一个具有数组中最后一个国家/地区名称的对象。您应该每次都在循环内创建一个 newRecord。

将此行移到 for 循环内，它应该可以正常工作。

let newRecord = NSEntityDescription.insertNewObjectForEntityForName("CountryList", inManagedObjectContext: context) as NSManagedObject

请注意，您正在创建一个核心数据管理对象并在循环内更改它，并且保存会多次保存同一对象。如果要保存多个对象，则必须每次创建一个新对象，设置其值，然后保存。您还可以将保存部分移到循环之外。

func writeData () {
    let appDel = UIApplication.sharedApplication().delegate as! AppDelegate
    let context = appDel.managedObjectContext
    let timestamp = NSDate()
    for geo in geoArray {
        let newRecord = NSEntityDescription.insertNewObjectForEntityForName("CountryList", inManagedObjectContext: context) as NSManagedObject
        newRecord.setValue(timestamp, forKey: "dateUploaded")
        newRecord.setValue(String(geo["CountryName"]!), forKey: "countryName")
    }
    do {
        try context.save()
        print("Saved successfully")
    } catch _ {
        print("there was issue saving data!")
    }

}