用关系类保存coredata中的数据？

我有一类Place &其他类作为Address。现在一个地方只有一个地址，所以我必须创造，当我试图挽救地方，那我不能够做一个relationship.Now。下面是代码我为这个功能写了。用关系类保存coredata中的数据？

if #available(iOS 10, *) { 
      placeInfo = NSEntityDescription.insertNewObject(forEntityName: "PlaceInfo", into: appDelegate.persistentContainer.viewContext) as? PlaceInfo 
     } else { 
      placeInfo = NSEntityDescription.insertNewObject(forEntityName: "PlaceInfo", into: appDelegate.managedObjectContext!) as? PlaceInfo 
     } 
      var cordinates:[String] = [] 
      placeInfo?.title = Place.shared.title ?? "" 
      placeInfo?.desc = Place.shared.desc ?? "" 
      placeInfo?.id = "Place_" + String(Utility.shared.currentTimeStamp()) 
      let spotLocation = Place.shared.address 

      if let lat = spotLocation?.lat, let long = spotLocation?.long { 
       cordinates = [lat.toString(),long.toString()] 
      } 
      let address = NSEntityDescription.insertNewObject(forEntityName: "PlaceAddress", into: appDelegate.managedObjectContext!) as? PlaceAddress 
      address?.street = "Street" 
      address?.landmark = "LANDMARK" 
      address?.city = "MYCITY" 
      address?.state = "SATTE" 
      address?.state = "INDIA" 
      address?.pincode = "1256325" 

      placeInfo?.isuploaded = true 
      if let spotid = placeInfo?.id { 
       // saveMediaToDB(id: spotid) 
      } 
      placeInfo?.address_rel = address

Placeinfo类

import Foundation 
import CoreData 


extension PlaceInfo { 

    @nonobjc public class func fetchRequest() -> NSFetchRequest<PlaceInfo> { 
     return NSFetchRequest<PlaceInfo>(entityName: "PlaceInfo") 
    } 

    @NSManaged public var desc: String? 
    @NSManaged public var hasmedia: Bool 
    @NSManaged public var id: String? 
    @NSManaged public var isuploaded: Bool 
    @NSManaged public var title: String? 
    @NSManaged public var address_rel: PlaceAddress? 
    @NSManaged public var files_rel: NSSet? 

} 

// MARK: Generated accessors for files_rel 
extension PlaceInfo { 

    @objc(addFiles_relObject:) 
    @NSManaged public func addToFiles_rel(_ value: FilesInfo) 

    @objc(removeFiles_relObject:) 
    @NSManaged public func removeFromFiles_rel(_ value: FilesInfo) 

    @objc(addFiles_rel:) 
    @NSManaged public func addToFiles_rel(_ values: NSSet) 

    @objc(removeFiles_rel:) 
    @NSManaged public func removeFromFiles_rel(_ values: NSSet) 

}

来源

2017-06-21 Techiee

为什么你可选择downcast'as？ PlaceInfo'和'as？ PlaceAddress'？这些类在编译时肯定存在。强制downcast不能失败，否则会显示开发人员/设计错误。然后你摆脱所有难看的问号。你也应该为'PlaceAddress'初始值设定项执行条件编译'if #available（iOS 10，*）'。 – vadian

你有没有添加下面的代码行？

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

来源

2017-06-21 13:53:09 SP74

用关系类保存coredata中的数据？

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