隔離時發生核心數據錯誤：無法在NSManagedObject類上調用指定的初始化程序

Question

我有一個視圖控制器，當點擊mapView上的圖釘時，它會與另一個視圖控制器相連。 “ Pin”是一個NSManagedObject，它在被發送到第二個視圖控制器之前（在其中函數使用實際圖像填充），在其中填充了緯度和經度。

我的didSelect函數完成后並且在我的performSegue函數被調用之前，出現錯誤“ CoreData：錯誤：無法在NSManagedObject類'Pin'上調用指定的初始化程序”。

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

@NSManaged public var latitude: Double
@NSManaged public var longitude: Double
@NSManaged public var images: NSSet?

這是課程：

convenience init(latitude: Double, longitude: Double, context: NSManagedObjectContext) {
    if let entity = NSEntityDescription.entity(forEntityName: "Pin", in: context) {
        self.init(entity: entity, insertInto: context)
        self.latitude = latitude
        self.longitude = longitude
    } else {
        fatalError("Unable to find entity name")
    }
}

我嘗試將pin聲明為可選，並用“！”強制聲明。 這兩個選項均無效。 根據我在網上學習和閱讀的許多文章，我將需要使用指定的初始化程序來初始化pin變量。 這是我在視圖控制器類頂部的嘗試，但也沒有用。

var pin = Pin.init(entity: NSEntityDescription.entity(forEntityName: "Pin", in: CoreDataStack.sharedInstance().context)!, insertInto: CoreDataStack.sharedInstance().context)

創建圖釘：

    // Create the annotation
    let touchPoint = gestureRecognizer.location(in: mapView)
    let newCoordinate = self.mapView.convert(touchPoint, toCoordinateFrom:self.mapView)
    let annotation = MKPointAnnotation()
    annotation.coordinate = newCoordinate


    pin = Pin(latitude: annotation.coordinate.latitude, longitude: annotation.coordinate.longitude, context: CoreDataStack.sharedInstance().context)
    let pinAnnotation = PinAnnotation(objectID: pin.objectID, title: nil, subtitle: nil, coordinate: annotation.coordinate)

    // Add the annotation
    mapView.addAnnotation(pinAnnotation)
    CoreDataStack.sharedInstance().saveContext()

在didSelect中選擇引腳：

do {
        let pinAnnotation = view.annotation as! PinAnnotation
        let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Pin")
        let predicate = NSPredicate(format: "latitude == %@ AND longitude == %@", argumentArray: [pinAnnotation.coordinate.latitude, pinAnnotation.coordinate.longitude])
        fetchRequest.predicate = predicate
        let pins = try CoreDataStack.sharedInstance().context.fetch(fetchRequest) as? [Pin]
        pin = pins![0]
    } catch let error as NSError {
        print("failed to get pin by object id")
        print(error.localizedDescription)
        return
    }
        self.performSegue(withIdentifier: "collectionViewSegue", sender: self)

...並執行以下命令：

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "collectionViewSegue" {
        let controller = segue.destination as! CollectionViewController
        print("CoreDataStack context in segue= \(CoreDataStack.sharedInstance().context)")
            controller.selectedPin = pin
            if let images = pin.images?.allObjects as? [Images] {
                controller.photos = images
            }
        print("PrepareForSegue pin properties are: \n latitude: \(pin.latitude) \n longitude: \(pin.longitude)")
        }
}

我想念什么？

Answer 1

我通過在類的開頭使變量聲明為可選來解決此問題：

var selectedPin: Pin?

...並在我的長按手勢中以不同的方式初始化Recognizer函數：

    @objc func handleLongPress(_ gestureRecognizer : UIGestureRecognizer) {
    if gestureRecognizer.state != .began { return }
    print("Tap gesture recognized")

    // Create the annotation
    let touchPoint = gestureRecognizer.location(in: mapView)
    let newCoordinate = self.mapView.convert(touchPoint, toCoordinateFrom:self.mapView)
    let annotation = MKPointAnnotation()
    annotation.coordinate = newCoordinate

    // Initialize NSManagedObject 'Pin' with properties
    selectedPin = Pin(context: CoreDataStack.sharedInstance().context)
    selectedPin?.latitude = annotation.coordinate.latitude
    selectedPin?.longitude = annotation.coordinate.longitude

    if let selectedPin = selectedPin {
    let pinAnnotation = PinAnnotation(objectID: selectedPin.objectID, title: nil, subtitle: nil, coordinate: annotation.coordinate)

    // Add the annotation
    mapView.addAnnotation(pinAnnotation)
    }

    CoreDataStack.sharedInstance().saveContext()
    print("This is what the ole save looks like: \(CoreDataStack.sharedInstance().context)")
}