import UIKit
import CoreData

class ViewController: UIViewController {
var canVasView = UIImageView()
@objc func hhh() {
    let photo = self.canVasView.image
    let data = photo!.pngData()

    if cdHandler.saveObject(pic:  data!){
    }
}
}

import UIKit
import CoreData

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, UNUserNotificationCenterDelegate {

var window: UIWindow?



class cdHandler: NSObject {

    private class func getContext() -> NSManagedObjectContext {
        let appdeleagetzz = UIApplication.shared.delegate as! AppDelegate
        return appdeleagetzz.persistentContainer.viewContext
    }
    class func saveObject(pic: Data) -> Bool {
        let context = getContext()
        let entity = NSEntityDescription.entity(forEntityName: "User", in: context)
        let managedObject = NSManagedObject(entity: entity!, insertInto: context)
        managedObject.setValue(pic, forKey:"pic")
        do {
            try context.save()
            return true

        } catch {
            return false

        }
    }
    class func deletObject(user: User) -> Bool {
        let context = getContext()
        context.delete(user)

        do {
            try context.save()
            return true
        } catch {
            return false

        }
    }

    class func fetchObject() -> [User]? {

        do {
            let context = getContext()
            return try context.fetch(User.fetchRequest())
        } catch {
            return [User]()
        }
    }

}
}