CoreData Swift: how to save and load data?

Question

I am writing an iOS game in Swift, and in the end I wanted to include a shortcut in it. I think the save function is correct, but the load is one - this is a problem that gives me problems. I already created an entity ("BestScores") and attributes ("classicBestScoreTF"):

To save the recorder:

var bestscore25 = 1000 var score: int func savescore() { var appDel: AppDelegate = (UIApplication.sharedApplication().delegate as AppDelegate) var context:NSManagedObjectContext = appDel.managedObjectContext! var score25: AnyObject! = NSEntityDescription.insertNewObjectForEntityForName("BestScores", inManagedObjectContext: context) as NSManagedObject score25.setValue(score, forKey: "classicBestScoreTF") context.save(nil) } func loadscore() { var appDel: AppDelegate = (UIApplication.sharedApplication().delegate as AppDelegate) var context:NSManagedObjectContext = appDel.managedObjectContext! bestScore25 = valueForKey("classicBestScoreTF") as Int } func endgame() { if score > bestScore25 { savescore() loadscore() bestScoreLabel.text = "Best Score: \(bestScore25)" } if score < bestscore { loadscore() bestScoreLabel.text = "Best Score: \(bestScore25)" } } 

This does not work :( Please help!

Answer 1

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() } 

Data loading:

 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)! 

Answer 2

To save data you should use:

 context.insertNewObjectForEntityForName(...) 

And when loading data, it should be:

context.valueForKey (...)

However, I'm not sure if this is even the correct syntax, since you may need to get an array of entities and then get an object with index 0. In this note, why are you using basic data for high scores? You might want to explore custom defaults or icloud, Core data is more for databases.

Answer 3

Updated for Swift:

Below is used a simple code to load, insert, delete date;

 import UIKit import CoreData class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, UIImagePickerControllerDelegate, UINavigationControllerDelegate{ // MARK:- Variable Declarations @IBOutlet weak var mTableView: UITableView! var manageObjectContext: NSManagedObjectContext! var eventArray = [Event]() // MARK:- ViewController LifeCycle Methods override func viewDidLoad() { super.viewDidLoad() self.title = "Event Reminder" manageObjectContext = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext self.loadSaveData() } override func viewWillAppear(_ animated: Bool) { // Remove empty cell from tableview mTableView.tableFooterView = UIView(frame: .zero) } // MARK:- TableView DataSource and Delegate Methods func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return eventArray.count } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell = tableView.dequeueReusableCell(withIdentifier: "ViewControllerTableViewCell")! as! ViewControllerTableViewCell cell.layer.cornerRadius = 05 let eventArrayItem = eventArray[indexPath.row] if let eventImage = UIImage(data: (eventArrayItem.event_image! as Data)){ cell.mImageView.image = eventImage } cell.mEventHeadingLabel.text = eventArrayItem.event_heading cell.mShortDescriptionLabel.text = eventArrayItem.event_description return cell } // To delete Particular cell/row from tableview func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) { let eventArrayItem = eventArray[indexPath.row] if editingStyle == .delete { manageObjectContext.delete(eventArrayItem) do { try manageObjectContext.save() } catch let error as NSError { print("Error While Deleting Note: \(error.userInfo)") } } self.loadSaveData() } // MARK:- IBAction Methods @IBAction func actionOnPlusButton(_ sender: Any) { let imagePicker = UIImagePickerController() imagePicker.sourceType = .photoLibrary imagePicker.delegate = self self.present(imagePicker, animated: true, completion: nil) } // MARK:- ImagePicker Delegate Methods func imagePickerControllerDidCancel(_ picker: UIImagePickerController) { picker.dismiss(animated: true, completion: nil) } func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) { if let mImage = info[UIImagePickerControllerOriginalImage] as? UIImage{ picker.dismiss(animated: true, completion: { self.createEventItemWith(selectedImage: mImage) }) } } // MARK:- Instance Methods func createEventItemWith(selectedImage: UIImage) { let eventItem = Event(context: manageObjectContext) let alertController = UIAlertController(title: "Add Event", message: "Enter event and it description", preferredStyle: .alert) let saveAction = UIAlertAction(title: "Save", style: .default, handler: { alert -> Void in let eventNameTextField = alertController.textFields![0] as UITextField let descriptionTextField = alertController.textFields![1] as UITextField print("firstName \(String(describing: eventNameTextField.text)), secondName \(String(describing: descriptionTextField.text))") if eventNameTextField.text != "" || descriptionTextField.text != ""{ eventItem.event_heading = eventNameTextField.text eventItem.event_description = descriptionTextField.text eventItem.event_image = NSData(data: UIImageJPEGRepresentation(selectedImage, 0.3)!) do{ try self.manageObjectContext.save() self.loadSaveData() }catch{ print("Could not save data: \(error.localizedDescription)") } }else{ self.showAlertMessageToUser(title: "Alert", messageToUser: "Fields should not be empty, Please enter given info...") } }) let cancelAction = UIAlertAction(title: "Cancel", style: .default, handler: { (action : UIAlertAction!) -> Void in self.manageObjectContext.reset() }) alertController.addTextField { (textField : UITextField!) -> Void in textField.placeholder = "Enter event Name" } alertController.addTextField { (textField : UITextField!) -> Void in textField.placeholder = "Enter event description in short" } alertController.addAction(saveAction) alertController.addAction(cancelAction) self.present(alertController, animated: true, completion: nil) } func showAlertMessageToUser(title: String, messageToUser: String) { let alert = UIAlertController(title: title, message: messageToUser, preferredStyle: UIAlertControllerStyle.alert) alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.default, handler: nil)) self.present(alert, animated: true, completion: nil) } func loadSaveData() { let eventRequest: NSFetchRequest<Event> = Event.fetchRequest() do{ eventArray = try manageObjectContext.fetch(eventRequest) self.mTableView.reloadData() }catch { print("Could not load save data: \(error.localizedDescription)") } } } 

Answer 4

Swift 5

Step 1. Create a simple application with the CoreData option

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

Step 3. Your AppDelegate should have basic data stack methods

Step 4. Make sure you have a quick code as shown below

 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 the device and look at the log for the results of the master data.

Answer 5

UIKit import CoreData import

ViewController Class: UIViewController {

 let nameTxt: UITextField = { let td = UITextField() td.translatesAutoresizingMaskIntoConstraints = false td.placeholder = "Enter Id" td.borderStyle = .line td.layer.borderWidth = 1 td.layer.borderColor = UIColor.lightGray.cgColor return td }() let doneBt: UIButton = { let bt = UIButton() bt.translatesAutoresizingMaskIntoConstraints = false bt.setTitle("DONE", for: .normal) bt.setTitleColor(.white, for: .normal) bt.addTarget(self, action: #selector(handleDoneBt), for: .touchUpInside) bt.backgroundColor = UIColor.blue return bt }() @objc func handleDoneBt() { saveData() } override func viewDidLoad() { super.viewDidLoad() // Do any additional setup after loading the view, typically from a nib. view.backgroundColor = .white setupView() setupLayout() } func saveData() { guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {return} let manageContent = appDelegate.persistentContainer.viewContext let userEntity = NSEntityDescription.entity(forEntityName: "Users", in: manageContent)! let users = NSManagedObject(entity: userEntity, insertInto: manageContent) users.setValue(1, forKeyPath: "id") users.setValue(nameTxt.text, forKeyPath: "name") users.setValue(123, forKeyPath: "mobile") do{ try manageContent.save() }catch let error as NSError { print("could not save . \(error), \(error.userInfo)") } fetchData() } func fetchData() { guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {return} let manageContent = appDelegate.persistentContainer.viewContext let fetchData = NSFetchRequest<NSFetchRequestResult>(entityName: "Users") do { let result = try manageContent.fetch(fetchData) for data in result as! [NSManagedObject]{ print(data.value(forKeyPath: "id") as Any) print(data.value(forKeyPath: "name") as Any) } }catch { print("err") } } func setupView() { view.addSubview(nameTxt) view.addSubview(doneBt) } func setupLayout(){ NSLayoutConstraint.activate([ nameTxt.centerXAnchor.constraint(equalTo: view.centerXAnchor), nameTxt.centerYAnchor.constraint(equalTo: view.centerYAnchor), nameTxt.widthAnchor.constraint(equalToConstant: 160), nameTxt.heightAnchor.constraint(equalToConstant: 30), doneBt.topAnchor.constraint(equalTo: nameTxt.bottomAnchor,constant: 6), doneBt.leftAnchor.constraint(equalTo: nameTxt.leftAnchor,constant: 8), doneBt.widthAnchor.constraint(equalToConstant: 120), doneBt.heightAnchor.constraint(equalToConstant: 36) ]) } 

}

DISPLAY IN TABLEVIEW

func fetchData () {

  guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {return} let manageContent = appDelegate.persistentContainer.viewContext let fetchData = NSFetchRequest<NSFetchRequestResult>(entityName: "Users") do { let result = try manageContent.fetch(fetchData) allData = result as! [NSManagedObject] tbl.reloadData() }catch { print("err") } } var allData = [NSObject]() 

func tableView (_ tableView: UITableView, section numberOfRowsInSection: Int) → Int {return allData.count}

 func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath) as! tblCell cell.lbl.text = allData[indexPath.row].value(forKey: "name") as? String return cell } 

func tableView (_ tableView: UITableView, commit editStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {

  if editingStyle == .delete { let task = allData[indexPath.row] guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {return} let manageContent = appDelegate.persistentContainer.viewContext manageContent.delete(task as! NSManagedObject) (UIApplication.shared.delegate as! AppDelegate).saveContext() do { try manageContent.save() } catch { print("Fetching Failed") } } fetchData() }