Swift: CoreData Conforming to MKAnnotation - swift

Question

I am attempting to implement my custom CoreData Carpark entity to conform to MKAnnotation like how we could make a class object conform to MKAnnotation.
I adapted my implementation from the following posts: this, this.
My implementation so far:
//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)
}
The above code would throw the error:
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[Carpark coordinate]:
unrecognized selector sent to instance 0x60400009e690'
Is there a way that we could make CoreData conform to MKAnnotation like how we could do it for a class object? Similar to something like this?:
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!)
}
}
Any advice is much appreciated, thanks.

Answer 1

You need to make your coordinate property public to be seen outside your module (outside like in the MapView framework). Maybe this is also the reason you need to cast your array.
This is my definition
public class Location: NSManagedObject, MKAnnotation {
public var coordinate: CLLocationCoordinate2D {
return CLLocationCoordinate2DMake(latitude, longitude)
}
//....more code
}
And in my view controller I have a property
var locations = [Location]()
And I fetch into it and adds to map view like this
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)
}

Answer 2

I managed to solve it by setting Codegen to Manual/None, and properties are then accessible.