CoreData Swift: How to save and load data?

Swift 5

Step 1. Create Simple app with CoreData option

Step 2. Open .xcdatamodeld file and add Entity, Attributes this way

Step 3. your AppDelegate should have Core Data stack methods

Step 4. Make sure you have swift code snipe as following

import UIKit
import CoreData

class ViewController: UIViewController {

    // MARK: Variables declearations
    let appDelegate = UIApplication.shared.delegate as! AppDelegate //Singlton instance
    var context:NSManagedObjectContext!

    // MARK: View Controller life cycle methods
    override func viewDidLoad() {
        super.viewDidLoad()

        openDatabse()
    }

    // MARK: Methods to Open, Store and Fetch data
    func openDatabse()
    {
        context = appDelegate.persistentContainer.viewContext
        let entity = NSEntityDescription.entity(forEntityName: "Users", in: context)
        let newUser = NSManagedObject(entity: entity!, insertInto: context)
        saveData(UserDBObj:newUser)
    }

    func saveData(UserDBObj:NSManagedObject)
    {
        UserDBObj.setValue("RDC", forKey: "username")
        UserDBObj.setValue("1234", forKey: "password")
        UserDBObj.setValue("21", forKey: "age")

        print("Storing Data..")
        do {
            try context.save()
        } catch {
            print("Storing data Failed")
        }

        fetchData()
    }

    func fetchData()
    {
        print("Fetching Data..")
        let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Users")
        request.returnsObjectsAsFaults = false
        do {
            let result = try context.fetch(request)
            for data in result as! [NSManagedObject] {
                let userName = data.value(forKey: "username") as! String
                let age = data.value(forKey: "age") as! String
                print("User Name is : "+userName+" and Age is : "+age)
            }
        } catch {
            print("Fetching data Failed")
        }
    }
}

Step 5. Run on Device and see log for core data results

Saving data:

var person = NSEntityDescription.insertNewObjectForEntityForName("Person", 
inManagedObjectContext: self.managedObjectContext!) as Person
person.name = "Mary"
person.age = Float(arc4random() % 100)

var error : NSError? = nil
if !self.managedObjectContext!.save(&error) {
    NSLog("Unresolved error \(error), \(error!.userInfo)")
    abort()
}

Loading data:

var error: NSError? = nil
var fReq: NSFetchRequest = NSFetchRequest(entityName: "Frases")    
fReq.predicate = NSPredicate(format: "id contains[c] %@", String(day))
var sorter: NSSortDescriptor = NSSortDescriptor(key: "id" , ascending: false)
fReq.sortDescriptors = [sorter]
fReq.returnsObjectsAsFaults = false
let result : [AnyObject] = self.managedObjectContext!.executeFetchRequest(fReq, error:&error)!