Core Data

import CoreData

var people: [NSManagedObject] = []

func deleteFromCD()
{
    guard let appDelegate =
        UIApplication.shared.delegate as? AppDelegate else {
            return
    }

    let managedContext = appDelegate.persistentContainer.viewContext

    let firstPerson = people[0]
    managedContext.delete(firstPerson)

    do {
        try managedContext.save()
    } catch {
        let saveError = error as NSError
        print(saveError)
    }
}


func loadFromCD()
{
    guard let appDelegate =
        UIApplication.shared.delegate as? AppDelegate else {
            return
    }

    let managedContext = appDelegate.persistentContainer.viewContext

    let fetchRequest = NSFetchRequest<NSManagedObject>(entityName: "Person")


    let sortDescriptor = NSSortDescriptor(key: "name", ascending: true)
    let sortDescriptors = [sortDescriptor]
    fetchRequest.sortDescriptors = sortDescriptors

    let resultPredicate = NSPredicate(format: "name = 'Bill'")
    fetchRequest.predicate = resultPredicate

    do {
        people = try managedContext.fetch(fetchRequest)
    } catch let error as NSError {
        print("Could not fetch. \(error), \(error.userInfo)")
    }
}

func saveToCD()
{
    guard let appDelegate =
        UIApplication.shared.delegate as? AppDelegate else {
            return
    }

    let managedContext = appDelegate.persistentContainer.viewContext

    let entity = NSEntityDescription.entity(forEntityName: "Person", in: managedContext)!

    let person = NSManagedObject(entity: entity, insertInto: managedContext)

    person.setValue("Apa", forKeyPath: "name")

    do {
        try managedContext.save()
        people.append(person)
    } catch let error as NSError {
        print("Could not save. \(error), \(error.userInfo)")
    }
}