Remplir TableView à partir de CoreData avec NSFetchRequest - SWIFT3 Xcode 8

Question

J'ai besoin de remplir ma vue de table avec les données de mes données de base. Je peux afficher mes lignes mais, je ne peux pas remplir mon tableview! J'utilise swift 3 et Xcode 8. Ceci est mon code, dans ce contrôleur je dois afficher la liste.

class iTableViewController: UITableViewController, NSFetchedResultsControllerDelegate{ 
@IBOutlet var iTableView: UITableView! 


override func viewDidLoad(){ 
    super.viewDidLoad() 

    iTableView.dataSource = self 
    iTableView.delegate = self 

    let appDelegate = UIApplication.shared.delegate as! AppDelegate 
    let managerContext = appDelegate.persistentContainer.viewContext 
    let interventsFetch = NSFetchRequest<NSFetchRequestResult>(entityName: "Intervento") 

    do{ 
     //results 
     let fetchedIntervents = try managerContext.fetch(interventsFetch) as! [Intervento] 

     for interv in fetchedIntervents{ 
      print(interv.stampRow()) 
     } 

     NSLog(String(fetchedIntervents.count)) 
    }catch{ 
     fatalError("Failed to fetch employees: \(error)") 
    } 
} 

override func didReceiveMemoryWarning() { 
    super.didReceiveMemoryWarning() 
} 

//number of sections 
override func numberOfSections(in tableView: UITableView) -> Int { 
    return 1 
} 

//numer of rows 
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { 
    return 1 
} 

//cell 
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { 
    let cell: UITableViewCell = UITableViewCell(style: UITableViewCellStyle.subtitle, reuseIdentifier: "cell") 

    cell.accessoryType = UITableViewCellAccessoryType.disclosureIndicator 

    //print the example cell 
    cell.textLabel?.text = "title" 
    cell.detailTextLabel?.text = "subtitle" 
    return cell 
} 

//swipe and delete 
override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath){ 
    if(editingStyle == UITableViewCellEditingStyle.delete){ 
     //TODO 
    } 
} 

// click cell 
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath){ 
    performSegue(withIdentifier: "segueDetail", sender: self) 
} 


override func viewDidAppear(_ animated: Bool){ 
    //iTableView.reloadData() 
} 

override func viewWillDisappear(_ animated: Bool) { 
    //iTableView.reloadData() 
    //fetchData() 
} 
} 

c'est ma classe

extension Intervento { 

@nonobjc public class func fetchRequest() -> NSFetchRequest<Intervento> { 
    return NSFetchRequest<Intervento>(entityName: "Intervento"); 
} 

@NSManaged public var cliente: Int32 
@NSManaged public var dataFine: String? 
@NSManaged public var dataInizio: String? 
@NSManaged public var descrizione: String? 
@NSManaged public var foto: String? 
@NSManaged public var id: Int32 
@NSManaged public var stato: String? 
@NSManaged public var tecnico: String? 

func stampRow()->String{ 
    let v1 = String(id) + " " + String(cliente) + " " 
    let v2 = dataInizio! + " " + dataFine! + " " 
    let v3 = stato! + " " + tecnico! + " " + descrizione! 
    return v1 + v2 + v3 
} 
} 

et c'est le mon code pour enregistrer les données (cela fonctionne)

@IBAction func addButton(_ sender: Any){ 
    //genero la data 
    let dateFormatter = DateFormatter() 
    dateFormatter.dateFormat = "dd-MM-yyyy HH:mm" 
    let strDate = dateFormatter.string(from: myDatePicker.date) 

    let appDelegate = UIApplication.shared.delegate as! AppDelegate 
    let managerContext = appDelegate.persistentContainer.viewContext 
    let newInt = NSEntityDescription.insertNewObject(forEntityName: "Intervento", into: managerContext) 

    newInt.setValue(1, forKey: "id") 
    newInt.setValue(strDate, forKey: "dataInizio") 
    newInt.setValue("", forKey: "dataFine") 
    newInt.setValue(2, forKey: "cliente") 
    newInt.setValue("Matt", forKey: "tecnico") 
    newInt.setValue(stato[1], forKey: "stato") 
    newInt.setValue("", forKey: "descrizione") 
    newInt.setValue("", forKey: "foto") 

    do{ 
     try managerContext.save() 
     print("saved") 
    }catch let error as NSError{ 
     //errore salvataggio 
     print("Could not fetch \(error), \(error.userInfo)") 
    } 
} 

Answer 1

Tout d'abord, votre classe doit mettre en œuvre ces protocoles:

UIViewController, UITableViewDataSource, UITableViewDelegate, NSFetchedResultsControllerDelegate 

Vous pouvez charger da ta d'un stockage persistant avec ce code:

//load data 

//persistant container 
let persistentContainer = NSPersistentContainer.init(name: "Model") 

// 
lazy var fetchedResultsController: NSFetchedResultsController<Intervento> = { 
    // Create Fetch Request 
    let fetchRequest: NSFetchRequest<Intervento> = Intervento.fetchRequest() 

    // Configure Fetch Request 
    fetchRequest.sortDescriptors = [NSSortDescriptor(key: "dataInizio", ascending: false)] 

    let appDelegate = UIApplication.shared.delegate as! AppDelegate 
    let managerContext = appDelegate.persistentContainer.viewContext 

    // Create Fetched Results Controller 
    let fetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: managerContext, sectionNameKeyPath: nil, cacheName: nil) 

    // Configure Fetched Results Controller 
    fetchedResultsController.delegate = self 

    return fetchedResultsController 
}() 

//carica 
func load(){ 
    //persistant container 
    persistentContainer.loadPersistentStores { (persistentStoreDescription, error) in 
     if let error = error { 
      print("Unable to Load Persistent Store") 
      print("\(error), \(error.localizedDescription)") 
     } else { 
      do { 
       try self.fetchedResultsController.performFetch() 
      } catch { 
       let fetchError = error as NSError 
       print("Unable to Perform Fetch Request") 
       print("\(fetchError), \(fetchError.localizedDescription)") 
      } 

     } 
    } 
} 

override func viewDidLoad(){ 
    super.viewDidLoad() 

    iTableView.delegate = self 
    iTableView.dataSource = self 

    // trigger load 
    load() 
} 

Vos données seront récupérées et montreront parce que vous avez délégué iTableViewController par cette ligne de code:

// Configure Fetched Results Controller 
fetchedResultsController.delegate = self 

Pour faire ce travail, votre ViewController doit être conforme au protocole NSFetchedResultsControllerDelegate, ici vous pouvez trouver une implémentation possibile:

extension iTableViewController: NSFetchedResultsControllerDelegate { 

func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) { 
    iTableView.beginUpdates() 
} 

func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) { 
    iTableView.endUpdates() 
} 

func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) { 
    switch (type) { 
    case .insert: 
     if let indexPath = newIndexPath { 
      iTableView.insertRows(at: [indexPath], with: .fade) 
     } 
     break; 
    case .delete: 
     if let indexPath = indexPath { 
      iTableView.deleteRows(at: [indexPath], with: .fade) 
     } 
     break; 
    case .update: 
     if let indexPath = indexPath, let cell = iTableView.cellForRow(at: indexPath) { 
      configureCell(cell, at: indexPath) 
     } 
     break; 
    case .move: 
     if let indexPath = indexPath { 
      iTableView.deleteRows(at: [indexPath], with: .fade) 
     } 

     if let newIndexPath = newIndexPath { 
      iTableView.insertRows(at: [newIndexPath], with: .fade) 
     } 
     break; 
    } 
} 
} 

en conclusion, c'est le pleine mise en œuvre de votre iTableViewController (j'ai inclus aussi le code nécessaire pour la suppression d'une ligne):

class iTableViewController: UIViewController, UITableViewDataSource, UITableViewDelegate{ 
@IBOutlet var iTableView: UITableView! 

//load data 

//persistant container 
let persistentContainer = NSPersistentContainer.init(name: "Model") 

// 
lazy var fetchedResultsController: NSFetchedResultsController<Intervento> = { 
    // Create Fetch Request 
    let fetchRequest: NSFetchRequest<Intervento> = Intervento.fetchRequest() 

    // Configure Fetch Request 
    fetchRequest.sortDescriptors = [NSSortDescriptor(key: "dataInizio", ascending: false)] 

    let appDelegate = UIApplication.shared.delegate as! AppDelegate 
    let managerContext = appDelegate.persistentContainer.viewContext 

    // Create Fetched Results Controller 
    let fetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: managerContext, sectionNameKeyPath: nil, cacheName: nil) 

    // Configure Fetched Results Controller 
    fetchedResultsController.delegate = self 

    return fetchedResultsController 
}() 

//carica 
func load(){ 
    //persistant container 
    persistentContainer.loadPersistentStores { (persistentStoreDescription, error) in 
     if let error = error { 
      print("Unable to Load Persistent Store") 
      print("\(error), \(error.localizedDescription)") 
     } else { 
      do { 
       try self.fetchedResultsController.performFetch() 
      } catch { 
       let fetchError = error as NSError 
       print("Unable to Perform Fetch Request") 
       print("\(fetchError), \(fetchError.localizedDescription)") 
      } 

     } 
    } 
} 


override func viewDidLoad(){ 
    super.viewDidLoad() 

    iTableView.delegate = self 
    iTableView.dataSource = self 

    // trigger load 
    load() 
} 

override func didReceiveMemoryWarning() { 
    super.didReceiveMemoryWarning() 
} 

//numero di sezioni 
func numberOfSections(in tableView: UITableView) -> Int { 
    return 1 
} 

//numero di righe 
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { 
    guard let quotes = fetchedResultsController.fetchedObjects else { return 0 } 
    return quotes.count 
} 

//gestisco la cella 
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { 
    //genero la cella 
    let cell: UITableViewCell = UITableViewCell(style: UITableViewCellStyle.subtitle, reuseIdentifier: "cell") 

    configureCell(cell, at:indexPath) 
    return cell 
} 

//swipe and delete 
func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath){ 
    if(editingStyle == .delete){ 

     // Fetch Quote 
     let quote = fetchedResultsController.object(at: indexPath) 

     // Delete Quote 
     quote.managedObjectContext?.delete(quote) 
    } 
} 

// click cell 
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath){ 
    performSegue(withIdentifier: "segueDetail", sender: self) 
} 


func configureCell(_ cell: UITableViewCell, at indexPath: IndexPath) { 

    //get intervento 
    let intervento = fetchedResultsController.object(at: indexPath) 

    //fill the cell 
    cell.textLabel?.text = intervento.dataInizio 
    cell.detailTextLabel?.text = "SOME_THING" 
} 

//quando appare aggiorno la table view 
override func viewDidAppear(_ animated: Bool){ 
    self.iTableView.reloadData() 
} 
} 

extension iTableViewController: NSFetchedResultsControllerDelegate { 

func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) { 
    iTableView.beginUpdates() 
} 

func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) { 
    iTableView.endUpdates() 
} 

func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) { 
    switch (type) { 
    case .insert: 
     if let indexPath = newIndexPath { 
      iTableView.insertRows(at: [indexPath], with: .fade) 
     } 
     break; 
    case .delete: 
     if let indexPath = indexPath { 
      iTableView.deleteRows(at: [indexPath], with: .fade) 
     } 
     break; 
    case .update: 
     if let indexPath = indexPath, let cell = iTableView.cellForRow(at: indexPath) { 
      configureCell(cell, at: indexPath) 
     } 
     break; 
    case .move: 
     if let indexPath = indexPath { 
      iTableView.deleteRows(at: [indexPath], with: .fade) 
     } 

     if let newIndexPath = newIndexPath { 
      iTableView.insertRows(at: [newIndexPath], with: .fade) 
     } 
     break; 
    } 
} 
} 

Ne pas oublier d'utiliser toujours le même contexte lorsque vous effectuez des opérations avec vos données (par exemple lorsque vous ajouter de nouvelles données).

let appDelegate = UIApplication.shared.delegate as! AppDelegate 
let managerContext = appDelegate.persistentContainer.viewContext 

Pour un exemple complet vous devriez regarder ici: https://github.com/bartjacobs/ExploringTheFetchedResultsControllerDelegateProtocol