核心数据中没有出现注释

Question

我正在创建一个应用程序，其中通过在地图上长按手势来创建注释并保存在 Core Data 中。我已经查看了这个resource，但我仍然无法解决地图上出现的注释问题。 Swift 2 对我来说一切都很好，不确定发生了什么变化以及我需要做些什么来修复，因为它看起来对我来说是正确的。谢谢！这是我的代码：

import UIKit
import MapKit
import CoreData

class MapViewController: UIViewController, MKMapViewDelegate {

//Variables

var locationManager = CLLocationManager()
var currentPins = [Pin]()
var gestureBegin: Bool = false

var sharedContext: NSManagedObjectContext {
    return CoreDataStack.sharedInstance().managedObjectContext
}

//Fetch All Pins

func fetchAllPins() -> [Pin] {
    let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Pin")
    do {
        return try sharedContext.fetch(fetchRequest) as! [Pin]
    } catch {
        print("Error In Fetch!")
        return [Pin]()
    }
}

//Outlets

@IBOutlet weak var mapView: MKMapView!

//Core Dat
override func viewDidLoad() {
    super.viewDidLoad()

    let longPressRecognizer = UILongPressGestureRecognizer(target: self, action: #selector(MapViewController.longPressGesture(longPress:)))
    longPressRecognizer.minimumPressDuration = 1.5
    mapView.addGestureRecognizer(longPressRecognizer)

    self.mapView.delegate = self

    addSavedPinsToMap()

}

//Add Saved Pin To Map

func addSavedPinsToMap() {
    currentPins = fetchAllPins()
    print("Pins Count in Core Data Is \(currentPins.count)")

    for currentPin in currentPins {
        let annotation = MKPointAnnotation()
        annotation.coordinate = currentPin.coordinate
        mapView.addAnnotation(annotation)
    }
}

//Long Press Gesture Recognizer

func longPressGesture(longPress: UIGestureRecognizer) {
    //Take Point
    let touchPoint = longPress.location(in: self.mapView)

    //Convert Point To Coordinate From View
    let touchMapCoordinate = mapView.convert(touchPoint, toCoordinateFrom: mapView)

    //Init Annotation
    let annotation = MKPointAnnotation()
    annotation.coordinate = touchMapCoordinate

    //Init New Pin
    let newPin = Pin(latitude: annotation.coordinate.latitude, longitude: annotation.coordinate.longitude, context: sharedContext)

    //Save To Core Data
    CoreDataStack.sharedInstance().saveContext()

    //Adding New Pin To Pins Array
    currentPins.append(newPin)

    //Add New Pin To Map
    mapView.addAnnotation(annotation)
}

} // End Class

这是我的核心数据文件：

import Foundation
import CoreData
import MapKit

//Pin Class
public class Pin: NSManagedObject {

var coordinate: CLLocationCoordinate2D {
    return CLLocationCoordinate2D(latitude: latitude, longitude: longitutde)
}

convenience init(latitude: Double, longitude: Double, context: NSManagedObjectContext) {
    if let ent = NSEntityDescription.entity(forEntityName: "Pin", in: context) {
        self.init(entity: ent, insertInto: context)
        self.latitude = latitude
        self.longitutde = longitude

    } else {
        fatalError("Unable To Find Entity Name!")
    }

}
}

还有其他核心数据文件：

import Foundation
import CoreData


extension Pin {

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

@NSManaged public var latitude: Double
@NSManaged public var longitutde: Double

}

Answer 1

发现我的 VC 中没有正确设置轻击手势。一旦我确定插座已连接到 VC，一切正常。