Swift:CoreData 符合 MKAnnotation

Question

我正在尝试实现我的自定义 CoreData Carpark 实体以符合 MKAnnotation，就像我们如何使 class 对象符合 >MKAnnotation.

我根据以下帖子调整了我的实现:this , this .

到目前为止我的实现:

//At Carpark+CoreDataClass.swift
import Foundation
import CoreData
import Mapkit

@objc(Carpark)
public class Carpark: NSManagedObject, MKAnnotation {

    var coordinate: CLLocationCoordinate2D {
        return CLLocationCoordinate2D(latitude: Double(self.lat), longitude: Double(self.long))
    }

    var title: String {
        return self.carparkName
    }

}

//At Carpark+CoreDataProperties.swift
import Foundation
import CoreData
import Mapkit

extension Carpark {

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

    @NSManaged public var carparkName: String?
    @NSManaged public var sundayAndPublicHolRate: String?
    @NSManaged public var saturdayRate: String?
    @NSManaged public var weekdayRate1: String?
    @NSManaged public var weekdayRate2: String?
    @NSManaged public var lat: Double
    @NSManaged public var long: Double
}

//At VC where I addAnnotations
var allCarparks: [Carpark]?
var nearbyCarparks = [Carpark]()
var searchedCarpark: Carpark!

func filterCarparksWithinRadius() {

    var allAnnotations = [Carpark]()

    let searchRadius = UserDefaults.standard.object(forKey: Constants.UserDefaults.SearchRadius) as! Double
    let searchedCarparkLocation = CLLocation(latitude: searchedCarpark.lat, longitude: searchedCarpark.long)

    allCarparks?.forEach({ (carpark) in
        let carparkLocation = CLLocation(latitude: carpark.lat, longitude: carpark.long)
        let distance = carparkLocation.distance(from: searchedCarparkLocation)

        if distance <= searchRadius && distance != 0 {
            nearbyCarparks.append(carpark)
            allAnnotations.append(carpark)
        }
    })

    allAnnotations.append(searchedCarpark)
    mapView.addAnnotations(allAnnotations as! [MKAnnotation]) //Problem here

    let zoomCoordinate = CLLocationCoordinate2D(latitude: searchedCarpark.lat, longitude: searchedCarpark.long)
    zoomToLocation(coordinate: zoomCoordinate)

}

上面的代码会抛出错误:

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[Carpark coordinate]: unrecognized selector sent to instance 0x60400009e690'

有没有一种方法可以让 CoreData 符合 MKAnnotation，就像我们对类对象所做的那样？类似于这样的东西？:

class Carpark: NSObject, MKAnnotation {
    var coordinate: CLLocationCoordinate2D
    var title: String?

    var carparkName: String?
    var lat: Double?
    var long: Double?

    init(carparkName: String?, lat: Double?, long: Double?) {
        self.title = carparkName
        self.carparkName = carparkName
        self.lat = lat
        self.long = long
        self.coordinate = CLLocationCoordinate2DMake(lat!, long!)
    }
}

非常感谢任何建议，谢谢。

Answer 1

您需要将坐标属性设为公共(public)，以便在模块外部(如 MapView 框架中的外部)可见。也许这也是您需要转换数组的原因。

这是我的定义

public class Location: NSManagedObject, MKAnnotation {

  public var coordinate: CLLocationCoordinate2D {
    return CLLocationCoordinate2DMake(latitude, longitude)
  }
  //....more code
}

在我的 View Controller 中我有一个属性

 var locations = [Location]()

我将其获取并添加到 map View 中，如下所示

private func updateLocations() {
    mapView.removeAnnotations(locations)

    let entity = Location.entity()
    let fetchRequest = NSFetchRequest<Location>()
    fetchRequest.entity = entity
    do {
        locations = try managedObjectContext.fetch(fetchRequest)
    } catch {
        fatalCoreDataError(error)
    }
    mapView.addAnnotations(locations)
}