Core Data Encoding Crash On Saving Context

Question

I'm getting the following error when saving the context of a custom managed object:

2020-05-10 20:43:40.432001-0400 Timecard[26285:12499267] [error] error: SQLCore dispatchRequest: exception handling request: <NSSQLSaveChangesRequestContext: 0x280c206c0> ,
 -[Timecard.Day encodeWithCoder:]: unrecognized selector sent to instance 0x281a0c460 with userInfo of (null)

I use a custom subclass of NSManagedObject to represent the "Week" entity. The Week entity is full of Day objects, which according to the error, seems to be where the issue is:

import Foundation


public class Day: NSObject, ObservableObject, Codable {

    var name: String
    @Published var date: Date
    @Published var jobs: [Job] = []

    var totalHours: Double {
        get {
            var totalHours = 0.0
            for job in jobs {
                totalHours = totalHours + job.totalHours
            }
            return totalHours
        }
    }

    var totalDollars: Double {
        get {
            var totalDollars = 0.0
            for job in jobs {
                totalDollars = totalDollars + job.totalDollars
            }
            return totalDollars
        }
    }

    init(name: String, date: Date) {
        self.name = name
        self.date = date
    }

    init(name: String) {
        self.name = name
        self.date = Date()
    }

    func add(job: Job) {
        jobs.append(job)
    }

    // Mark: - Codable Encoding & Decoding

    enum CodingKeys: String, CodingKey {
        case date
        case jobs
        case name
    }

    required public init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        name = try container.decode(String.self, forKey: .name)
        date = try container.decode(Date.self, forKey: .date)
        jobs = try container.decode([Job].self, forKey: .jobs)
    }

    public func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(name, forKey: .name)
        try container.encode(date, forKey: .date)
        try container.encode(jobs, forKey: .jobs)
    }
}

Week -> Day -> Job all conform to Codable and it works when saving to a Plist. It only crashes when I try to save the context.

Tom Harrington Tom Harrington · Accepted Answer · 2020-05-11T21:32:29

It looks like you're trying to use this type as a Core Data transformable attribute. Core Data transformable attributes must conform to NSCoding. Codable has a similar name and a similar purpose, but they are not the same and are not compatible with each other. If you want to use this type with a Core Data transformable attribute, it must conform to NSCoding.

Core Data Encoding Crash On Saving Context

2 Answers