Core Data insert - swift

Question

I try to learn Core Data and after many hours and a lot of tutorials, I am still confused. All the tutorials seem so complicated with so many elements involved. It would be very helpful if someone could give me an example of the most simple insert possible. (please without tables, navigation controllers... just insert a name and password)
I have created an entity of users with the attribute name and password
I have two textfields: name and password. I have the connection from the storyboard to the ViewController
I have a button
How can I save names and passwords when the user clicks to button?
#IBOutlet weak var name: UITextField!
#IBOutlet weak var password: UITextField!
#IBAction func button(_ sender: UIButton) {
}

Answer 1

First, do you have an NSManagedObjectContext available at this point? Assuming you do and it's called context
import UIKit
import CoreData
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
if let viewController = window?.rootViewController as? ViewController {
viewController.context = persistentContainer.viewContext
}
return true
}
// ... other functions
}
import CoreData
class ViewController: UIViewController {
#IBOutlet weak var name: UITextField!
#IBOutlet weak var password: UITextField!
var context: NSManagedObjectContext!
override func viewDidLoad() {
super.viewDidLoad()
assert(context != nil)
}
#IBAction func button(_ sender: UIButton) {
guard name.hasText || password.hasText else { return }
let newUser = User(context: context)
if let nameString = name.text {
newUser.name = nameString
}
if let passwordString = password.text {
newUser.password = passwordString
}
context.insert(newUser)
saveContext()
}
func saveContext() {
if context.hasChanges {
do {
try context.save()
} catch {
print(error.localizedDescription)
}
}
}
}

Answer 2

Very simple example.
Instantiate the context lazily in the view controller
lazy var context : NSManagedObjectContext = {
let appDelegate = UIApplication.shared.delegate as! AppDelegate
return appDelegate.persistentContainer.viewContext
}()
If it's going to be used only the in IBAction instantiate it temporarily in there (see commented out code)
Then in the IBAction write
#IBAction func button(_ sender: UIButton) {
guard name.hasText, !name.text!.first!.isWhitespace,
password.hasText, !password.text!.first!.isWhitespace else {
// show an alert that both text fields must not be empty and must not start with a whitespace characters.
return
}
// let appDelegate = UIApplication.shared.delegate as! AppDelegate
// let context = appDelegate.persistentContainer.viewContext
let user = User(context: context)
user.name = self.name.text!
user.password = self.password.text!
do {
try context.save()
} catch {
print(error)
}
}
Side note: To avoid ambiguity name the text fields more distinct for example
#IBOutlet weak var nameField: UITextField!
#IBOutlet weak var passwordField: UITextField!