A structure with the same name as the Core Data object type?

Okay, I made a sample project for you, going through a lot of difficulties. But I am posting the basic concept here.

You can get a sample project here . Although I downloaded the data from a local file .plist

. You can check how the function works loadPersonWithJSON(fromPath:)

. Just follow my code comments.

Suppose I have a Person Entity in mine Core-Data

with two properties String

name

and location

. From json, I am getting an array that is of type [[String:Any]]

. Now I want to map my json data to the main data object model.

enum CoreDataError: String, Error {
    case NoEntity = "ERROR: No Entity, Check the Entity Name"
}

enum JSONError: String, Error {
    case NoData = "ERROR: no data"
    case ConversionFailed = "ERROR: conversion from JSON failed"
}

typealias personJSONObjectType = [[String:String]]

class PersonTableViewController: UITableViewController {

    var person: [Person] = []

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        self.loadPersonWithJSON(fromPath: "your json URL in String format")
    }

    func loadPersonWithJSON(fromPath jsonURLString:String) {
        guard let jsonURL = URL(string: jsonURLString) else {
            print("Error creating an URL from \(jsonURLString)")
            return
        }
        URLSession.shared.dataTask(with: jsonURL) { (data, response, error) in
            do {
                guard let data = data else {
                    throw JSONError.NoData
                }
                guard let json = try JSONSerialization.jsonObject(with: data, options: []) as? personJSONObjectType else {
                    throw JSONError.ConversionFailed
                }

                // Here you have your json data. Now map this data to your model object.

                // First you need to have your shared App Delegate
                guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {
                    print("No shared AppDelegate")
                    return
                }

                // Use shared App Delegate to have the persistent containers view context as managed object context. This will be used to verify whether your Entity exists or not
                let managedObjectContext = appDelegate.persistentContainer.viewContext

                // Get the Entity in your core data model
                guard let entity = NSEntityDescription.entity(forEntityName: "Person", in: managedObjectContext) else {
                    throw CoreDataError.NoEntity
                }

                let persons = json.map({ (personInfo) -> Person in

                    let personName = personInfo["name"] as? String              // use appropriate key for "name"
                    let personLocation = personInfo["location"] as? String      // use appropriate key for "location"

                    // Get your object as Core data Managed object.
                    let aPerson = NSManagedObject(entity: entity, insertInto: managedObjectContext) as! Person

                    // Manipulate core data object with json data
                    aPerson.name = personName
                    aPerson.location = personLocation
                    // Manipulation done

                    return aPerson
                })

                self.person = persons
                self.tableView.reloadData()

            } catch let error as JSONError {
                print(error.rawValue)
            } catch let error as CoreDataError {
                print(error.rawValue)
            } catch let error as NSError {
                print(error.debugDescription)
            }
            }.resume()
    }
}

      

        
        
        
      

    

Additional resource

You can use the following table data source method to check if this works:

// MARK: - Table view data source

override func numberOfSections(in tableView: UITableView) -> Int {
    return 1
}

override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return self.person.count
}

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
    let aPerson = self.person[indexPath.row]
    cell.textLabel?.text = aPerson.name
    cell.detailTextLabel?.text = aPerson.location
    return cell
}