Swift 使用NSFetchRequest从CoreData填充TableView_Swift_Xcode_Uitableview_Core Data_Nsfetchrequest

Swift 使用NSFetchRequest从CoreData填充TableView

swift xcode uitableview core-data

Swift 使用NSFetchRequest从CoreData填充TableView,swift,xcode,uitableview,core-data,nsfetchrequest,Swift,Xcode,Uitableview,Core Data,Nsfetchrequest,我需要用核心数据中的数据填充表视图。我可以显示我的行，但我不能填充我的tableview！我使用Swift 3和Xcode 8。这是我的代码，在这个控制器中我必须显示列表 class iTableViewController: UITableViewController, NSFetchedResultsControllerDelegate{ @IBOutlet var iTableView: UITableView! override func viewDidLoad(){

我需要用核心数据中的数据填充表视图。我可以显示我的行，但我不能填充我的tableview！我使用Swift 3和Xcode 8。这是我的代码，在这个控制器中我必须显示列表

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()
}
}

首先，您的类应该实现以下协议：

UIViewController, UITableViewDataSource, UITableViewDelegate, NSFetchedResultsControllerDelegate

您可以使用以下代码从持久性存储器加载数据：

//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()
}

为了实现此功能，您的ViewController必须符合NSFetchedResultsControllerDelegate协议，在这里您可以找到一个可行的实现：

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;
    }
}
}

有关完整示例，请参见此处：

首先，您的类应实现以下协议：

UIViewController, UITableViewDataSource, UITableViewDelegate, NSFetchedResultsControllerDelegate

您可以使用以下代码从持久性存储器加载数据：

//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()
}

为了实现此功能，您的ViewController必须符合NSFetchedResultsControllerDelegate协议，在这里您可以找到一个可行的实现：

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;
    }
}
}

有关完整示例，请参见此处：

Swift 3.3

  lazy var fetchedResultsController: NSFetchedResultsController<SavedContact> = {
                    let fetchReqest: NSFetchRequest<SavedContact> = SavedContact.fetchRequest()
                    fetchReqest.sortDescriptors = [NSSortDescriptor(key: "id", ascending: true)]
                    let fetchedResultsController = NSFetchedResultsController(fetchRequest: fetchReqest, managedObjectContext: Database.shared.mainManagedObjectContext, sectionNameKeyPath: nil, cacheName: nil)
                    fetchedResultsController.delegate = self
                    return fetchedResultsController
                  }()

       override func viewDidLoad() {
           super.viewDidLoad()
           self.performFetch()
         }
       func performFetch() {
         do {
                 try self.fetchedResultsController.performFetch()
            } catch {
                 Debug.Log(message: "Error in fetching Contact \(error)")
            }
    }
    //MARK: - NSFetchResultcontrollerDelegate
    extension YourViewC: NSFetchedResultsControllerDelegate {

          func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
            self.tableView.reloadData()
          }
        }
// Database Class    
    private let _singletonInstance: Database = Database()

    class Database: NSObject {
         class var shared: Database {
                  return _singletonInstance
                 }

        override init() {
               super.init()
         }
        // Main Managed Object Context
        lazy var mainManagedObjectContext: NSManagedObjectContext = {

               let coordinator = self.persistentStoreCoordinator
               var mainManagedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
                mainManagedObjectContext.persistentStoreCoordinator = coordinator
                 return mainManagedObjectContext
           }()
    // Persistent Store Coordinator
         lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {

           let mOptions = [NSMigratePersistentStoresAutomaticallyOption: true,
                                    NSInferMappingModelAutomaticallyOption: true]
           let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
           let url = self.applicationDocumentsDirectory.appendingPathComponent("AppName.sqlite")
            var failureReason = "There was an error creating or loading the application's saved data."
            do {
                        try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url, options: mOptions)
                    } catch {
                        // Report any error we got.
                        var dict = [String: AnyObject]()
                        dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data" as AnyObject?
                        dict[NSLocalizedFailureReasonErrorKey] = failureReason as AnyObject?

                        dict[NSUnderlyingErrorKey] = error as NSError
                        let wrappedError = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
                        abort()
                    }
                    return coordinator
                }()
    // DB Directory and Path
          lazy var applicationDocumentsDirectory: URL = {

                    let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
                    let documentDirectoryURL = urls[urls.count - 1] as URL
                    let dbDirectoryURL = documentDirectoryURL.appendingPathComponent("DB")

                    if FileManager.default.fileExists(atPath: dbDirectoryURL.path) == false{
                        do{
                            try FileManager.default.createDirectory(at: dbDirectoryURL, withIntermediateDirectories: false, attributes: nil)
                        }catch{
                        }
                    }
                    return dbDirectoryURL
                }()
    }

Swift 3.3

  lazy var fetchedResultsController: NSFetchedResultsController<SavedContact> = {
                    let fetchReqest: NSFetchRequest<SavedContact> = SavedContact.fetchRequest()
                    fetchReqest.sortDescriptors = [NSSortDescriptor(key: "id", ascending: true)]
                    let fetchedResultsController = NSFetchedResultsController(fetchRequest: fetchReqest, managedObjectContext: Database.shared.mainManagedObjectContext, sectionNameKeyPath: nil, cacheName: nil)
                    fetchedResultsController.delegate = self
                    return fetchedResultsController
                  }()

       override func viewDidLoad() {
           super.viewDidLoad()
           self.performFetch()
         }
       func performFetch() {
         do {
                 try self.fetchedResultsController.performFetch()
            } catch {
                 Debug.Log(message: "Error in fetching Contact \(error)")
            }
    }
    //MARK: - NSFetchResultcontrollerDelegate
    extension YourViewC: NSFetchedResultsControllerDelegate {

          func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
            self.tableView.reloadData()
          }
        }
// Database Class    
    private let _singletonInstance: Database = Database()

    class Database: NSObject {
         class var shared: Database {
                  return _singletonInstance
                 }

        override init() {
               super.init()
         }
        // Main Managed Object Context
        lazy var mainManagedObjectContext: NSManagedObjectContext = {

               let coordinator = self.persistentStoreCoordinator
               var mainManagedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
                mainManagedObjectContext.persistentStoreCoordinator = coordinator
                 return mainManagedObjectContext
           }()
    // Persistent Store Coordinator
         lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {

           let mOptions = [NSMigratePersistentStoresAutomaticallyOption: true,
                                    NSInferMappingModelAutomaticallyOption: true]
           let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
           let url = self.applicationDocumentsDirectory.appendingPathComponent("AppName.sqlite")
            var failureReason = "There was an error creating or loading the application's saved data."
            do {
                        try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url, options: mOptions)
                    } catch {
                        // Report any error we got.
                        var dict = [String: AnyObject]()
                        dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data" as AnyObject?
                        dict[NSLocalizedFailureReasonErrorKey] = failureReason as AnyObject?

                        dict[NSUnderlyingErrorKey] = error as NSError
                        let wrappedError = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
                        abort()
                    }
                    return coordinator
                }()
    // DB Directory and Path
          lazy var applicationDocumentsDirectory: URL = {

                    let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
                    let documentDirectoryURL = urls[urls.count - 1] as URL
                    let dbDirectoryURL = documentDirectoryURL.appendingPathComponent("DB")

                    if FileManager.default.fileExists(atPath: dbDirectoryURL.path) == false{
                        do{
                            try FileManager.default.createDirectory(at: dbDirectoryURL, withIntermediateDirectories: false, attributes: nil)
                        }catch{
                        }
                    }
                    return dbDirectoryURL
                }()
    }

你的代码很混乱。UITableViewController包含预定义的UITableView实例，该实例具有连接的委托和数据源。您正在使用NSFetchedResultsController吗？这段代码与手动获取数据完全不同。数据源阵列在哪里？类名称应该以大写字母开头。PS：选中“核心数据”复选框创建新的主详细信息项目。您将免费获得所需的几乎全部代码。谢谢，我已经添加了我的类和用于保存在数据库中的代码。也许我需要使用NsFetchedResultController，但如何使用NSFetchedResultsController是处理核心数据获取的一种非常方便的方法。遵循我在第二条评论中的建议。@Matt这是一个使用NSFetchedResultsController的很好的参考：您的代码令人困惑。UITableViewController包含预定义的UITableView实例，该实例具有连接的委托和数据源。您正在使用NSFetchedResultsController吗？这段代码与手动获取数据完全不同。数据源阵列在哪里？类名称应该以大写字母开头。PS：选中“核心数据”复选框创建新的主详细信息项目。您将免费获得所需的几乎全部代码。谢谢，我已经添加了我的类和用于保存在数据库中的代码。也许我需要使用NsFetchedResultController，但如何使用NSFetchedResultsController是处理核心数据获取的一种非常方便的方法。按照我在第二条评论中的建议来做。@Matt这是一个很好的参考资料，可以使用NSFetchedResultsController进行分析：谢谢你的详细回答，Mariusz！马吕斯，为了得到详细的答案，他工作得很卖力！工作得很有魅力

  lazy var fetchedResultsController: NSFetchedResultsController<SavedContact> = {
                    let fetchReqest: NSFetchRequest<SavedContact> = SavedContact.fetchRequest()
                    fetchReqest.sortDescriptors = [NSSortDescriptor(key: "id", ascending: true)]
                    let fetchedResultsController = NSFetchedResultsController(fetchRequest: fetchReqest, managedObjectContext: Database.shared.mainManagedObjectContext, sectionNameKeyPath: nil, cacheName: nil)
                    fetchedResultsController.delegate = self
                    return fetchedResultsController
                  }()

       override func viewDidLoad() {
           super.viewDidLoad()
           self.performFetch()
         }
       func performFetch() {
         do {
                 try self.fetchedResultsController.performFetch()
            } catch {
                 Debug.Log(message: "Error in fetching Contact \(error)")
            }
    }
    //MARK: - NSFetchResultcontrollerDelegate
    extension YourViewC: NSFetchedResultsControllerDelegate {

          func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
            self.tableView.reloadData()
          }
        }
// Database Class    
    private let _singletonInstance: Database = Database()

    class Database: NSObject {
         class var shared: Database {
                  return _singletonInstance
                 }

        override init() {
               super.init()
         }
        // Main Managed Object Context
        lazy var mainManagedObjectContext: NSManagedObjectContext = {

               let coordinator = self.persistentStoreCoordinator
               var mainManagedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
                mainManagedObjectContext.persistentStoreCoordinator = coordinator
                 return mainManagedObjectContext
           }()
    // Persistent Store Coordinator
         lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {

           let mOptions = [NSMigratePersistentStoresAutomaticallyOption: true,
                                    NSInferMappingModelAutomaticallyOption: true]
           let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
           let url = self.applicationDocumentsDirectory.appendingPathComponent("AppName.sqlite")
            var failureReason = "There was an error creating or loading the application's saved data."
            do {
                        try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url, options: mOptions)
                    } catch {
                        // Report any error we got.
                        var dict = [String: AnyObject]()
                        dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data" as AnyObject?
                        dict[NSLocalizedFailureReasonErrorKey] = failureReason as AnyObject?

                        dict[NSUnderlyingErrorKey] = error as NSError
                        let wrappedError = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
                        abort()
                    }
                    return coordinator
                }()
    // DB Directory and Path
          lazy var applicationDocumentsDirectory: URL = {

                    let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
                    let documentDirectoryURL = urls[urls.count - 1] as URL
                    let dbDirectoryURL = documentDirectoryURL.appendingPathComponent("DB")

                    if FileManager.default.fileExists(atPath: dbDirectoryURL.path) == false{
                        do{
                            try FileManager.default.createDirectory(at: dbDirectoryURL, withIntermediateDirectories: false, attributes: nil)
                        }catch{
                        }
                    }
                    return dbDirectoryURL
                }()
    }