Swift - Custom MKPointAnnotation with Image

Question

I am trying to create a custom MKPointAnnotation to use on a map view. It looks very much like the one used in Apple's Photos:

I will be retrieving a number of photos from a server, along with their location. I then want to display an annotation like the one above, with the image inside the annotation.

I currently have a program that can add a normal MKPointAnnotation at the right coordinate, and can also retrieve the relevant photo from the server.

All I want is to style my MKPointAnnotation to look just like that.

I have tried following other answers but I think this is slightly different because I want to show an image on a template every time.

Answer 1

func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? from MKMapViewDelegate is the function you need to override.

It allows you to provide "custom" views for the each annotation. Within this function, you can either dequeue a custom view (subclass of MKAnnotationView) and set custom properties OR you can dequeue a regular MKAnnotationView which has a property image.

You can set that property to display custom images. I'd rather use my own annotationView anyway as you can add custom layouts (labels, imageViews, etc..) and themes (colours, layers, etc..).

Example:

//
//  ViewController.swift
//  Maps
//
//  Created by Brandon T on 2017-02-20.
//  Copyright © 2017 XIO. All rights reserved.
//

import UIKit
import MapKit


class ImageAnnotation : NSObject, MKAnnotation {
    var coordinate: CLLocationCoordinate2D
    var title: String?
    var subtitle: String?
    var image: UIImage?
    var colour: UIColor?

    override init() {
        self.coordinate = CLLocationCoordinate2D()
        self.title = nil
        self.subtitle = nil
        self.image = nil
        self.colour = UIColor.white
    }
}

class ImageAnnotationView: MKAnnotationView {
    private var imageView: UIImageView!

    override init(annotation: MKAnnotation?, reuseIdentifier: String?) {
        super.init(annotation: annotation, reuseIdentifier: reuseIdentifier)

        self.frame = CGRect(x: 0, y: 0, width: 50, height: 50)
        self.imageView = UIImageView(frame: CGRect(x: 0, y: 0, width: 50, height: 50))
        self.addSubview(self.imageView)

        self.imageView.layer.cornerRadius = 5.0
        self.imageView.layer.masksToBounds = true
    }

    override var image: UIImage? {
        get {
            return self.imageView.image
        }

        set {
            self.imageView.image = newValue
        }
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

class ViewController: UIViewController, MKMapViewDelegate {

    var mapView: MKMapView!
    var locationManager: CLLocationManager!

    override func viewDidLoad() {
        super.viewDidLoad()


        self.initControls()
        self.doLayout()
        self.loadAnnotations()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

    func initControls() {
        self.mapView = MKMapView()

        self.mapView.isRotateEnabled = true
        self.mapView.showsUserLocation = true
        self.mapView.delegate = self

        let center = CLLocationCoordinate2DMake(43.761539, -79.411079)
        let region = MKCoordinateRegionMake(center, MKCoordinateSpanMake(0.005, 0.005))
        self.mapView.setRegion(region, animated: true)
    }

    func doLayout() {
        self.view.addSubview(self.mapView)
        self.mapView.leftAnchor.constraint(equalTo: self.view.leftAnchor).isActive = true
        self.mapView.rightAnchor.constraint(equalTo: self.view.rightAnchor).isActive = true
        self.mapView.topAnchor.constraint(equalTo: self.view.topAnchor).isActive = true
        self.mapView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor).isActive = true
        self.mapView.translatesAutoresizingMaskIntoConstraints = false
    }

    func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
        if annotation.isKind(of: MKUserLocation.self) {  //Handle user location annotation..
            return nil  //Default is to let the system handle it.
        }

        if !annotation.isKind(of: ImageAnnotation.self) {  //Handle non-ImageAnnotations..
            var pinAnnotationView = mapView.dequeueReusableAnnotationView(withIdentifier: "DefaultPinView")
            if pinAnnotationView == nil {
                pinAnnotationView = MKPinAnnotationView(annotation: annotation, reuseIdentifier: "DefaultPinView")
            }
            return pinAnnotationView
        }

        //Handle ImageAnnotations..
        var view: ImageAnnotationView? = mapView.dequeueReusableAnnotationView(withIdentifier: "imageAnnotation") as? ImageAnnotationView
        if view == nil {
            view = ImageAnnotationView(annotation: annotation, reuseIdentifier: "imageAnnotation")
        }

        let annotation = annotation as! ImageAnnotation
        view?.image = annotation.image
        view?.annotation = annotation

        return view
    }


    func loadAnnotations() {
        let request = NSMutableURLRequest(url: URL(string: "https://i.imgur.com/zIoAyCx.png")!)
        request.httpMethod = "GET"

        let session = URLSession(configuration: URLSessionConfiguration.default)
        let dataTask = session.dataTask(with: request as URLRequest) { (data, response, error) in
            if error == nil {

                let annotation = ImageAnnotation()
                annotation.coordinate = CLLocationCoordinate2DMake(43.761539, -79.411079)
                annotation.image = UIImage(data: data!, scale: UIScreen.main.scale)
                annotation.title = "Toronto"
                annotation.subtitle = "Yonge & Bloor"


                DispatchQueue.main.async {
                    self.mapView.addAnnotation(annotation)
                }
            }
        }

        dataTask.resume()
    }
}