SpacePod 32 CoreData Decodable NSManagedObject

Previously we added a CoreData model named Nasa. Let’s rename it to Pod to mirror our existing object, and then work through the resulting build errors so that our app is using the new object.



  1. Mirror CoreData Model and Pod Model
  2. Update Pod to work with CoreData
  3. Update our views to ensure everything still works as before


  1. Rename Nasa to Pod
  2. Change Codegen to Category/Extension, and
  3. Set module to current and save
  4. import CoreData
  5. NSManagedObject
  6. Delete properties in Pod
  7. Change Codble to Decodable
  8. Remove id
  9. add DecoderConfigurationError
  10. add CodingUserInfoKey
  11. add convenience
  12. add context
  13. add self.init
  14. add decoder.userInfo[CodingUserInfoKey.managedObjectContext] = PersistenceController.shared.container.viewContext
  15. add if let to optionals in views


1, 2, 3

<entity name="Pod" representedClassName=".Pod" syncable="YES" codeGenerationType="category">

4 to 13, Pod.swift Complete

import Foundation
import CoreData

class Pod: NSManagedObject, Decodable {

    private enum CodingKeys: String, CodingKey {
        case copyright
        case date
        case explanation
        case hdurl
        case mediaType
        case serviceVersion
        case title
        case url
        case thumbnailUrl

    enum DecoderConfigurationError: Error {
        case missingManagedObjectContext

    required convenience init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)

        guard let context = decoder.userInfo[CodingUserInfoKey.managedObjectText] as? NSManagedObjectContext else {
            throw DecoderConfigurationError.missingManagedObjectContext

        self.init(context: context)

        copyright = try container.decodeIfPresent(String.self, forKey: .copyright)
        date = try container.decodeIfPresent(Date.self, forKey: .date)
        explanation = try container.decode(String.self, forKey: .explanation)
        hdurl = try container.decodeIfPresent(URL.self, forKey: .hdurl)
        mediaType = try container.decode(String.self, forKey: .mediaType)
        serviceVersion = try container.decode(String.self, forKey: .serviceVersion)
        title = try container.decode(String.self, forKey: .title)
        url = try container.decodeIfPresent(URL.self, forKey: .url)
        thumbnailUrl = try container.decodeIfPresent(URL.self, forKey: .thumbnailUrl)

extension CodingUserInfoKey {
    static let managedObjectText = CodingUserInfoKey(rawValue: "managedObjectContext")!

14 Data+Extensions.swift

decoder.userInfo[CodingUserInfoKey.managedObjectContext] = PersistenceController.shared.container.viewContext

15 Optionals

Handle optionals in our views with if let... (for now)