display multiple annotations on mapview - arrays

Question

I've been looking around on stackoverflow for a solution but I haven't yet successfully implemented it. If someone can give me some tips on where the problem lies, thank you so much. Here is what I have so far
Here is location class
class Location: NSObject, MKAnnotation {
var title: String?
var coordinate: CLLocationCoordinate2D
init(title: String, coordinate: CLLocationCoordinate2D) {
self.title = title
self.coordinate = coordinate
}
Method to display all annotations.
func displayAllEventsPins() {
for event in events {
let address = event.location
geocoder.geocodeAddressString(address!, completionHandler: { (placemarks: [CLPlacemark]?, error: Error?) -> Void in
if let placemark = placemarks?.first {
let eventlat = placemark.location?.coordinate.latitude
let eventlong = placemark.location?.coordinate.longitude
let annotation = MKPointAnnotation()
annotation.title = event.name
annotation.coordinate = CLLocationCoordinate2D(latitude: eventlat!, longitude: eventlong!)
self.locations.append(Location(title: annotation.title!, coordinate: annotation.coordinate))
for location in self.locations {
let pin = MKPointAnnotation()
pin.title = location.title
pin.coordinate = location.coordinate
self.mapView.addAnnotation(pin)
}
}
})
}
}
Edited: The problem here is that annotations doesnt show up on mapview. I can only see the currentlocation pin and nothing else.
Edited: This is the call i used to drop user current location pin.
extension Search : CLLocationManagerDelegate {
func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {
if status == .authorizedWhenInUse {
locationManager.requestLocation()
}
}
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
//MARK: remove previous current pin for user location
mapView.removeAnnotation(newPin)
let location = locations.last! as CLLocation
let center = CLLocationCoordinate2DMake(location.coordinate.latitude, location.coordinate.longitude)
self.currentLocation = location
let region = MKCoordinateRegion(center: center, span: MKCoordinateSpanMake(0.03, 0.03))
mapView.setRegion(region, animated: true)
newPin.coordinate = location.coordinate
mapView.addAnnotation(newPin)
}
}
Here is the code in the viewDidLoad method:
override func viewDidLoad() {
super.viewDidLoad()
//MARK: Request Current Location
locationManager.delegate = self
locationManager.desiredAccuracy = kCLLocationAccuracyBest
locationManager.requestWhenInUseAuthorization()
locationManager.requestAlwaysAuthorization()
locationManager.requestLocation()
displayAllEventsPins()
}

Answer 1

This should work for you.
By the way, looping through your locations whilst in the events loop is just going to add duplicates of the same pin, which will be very bad on memory and it's not a good thing to do.
import UIKit
import MapKit
import Firebase
class ViewController: UIViewController, MKMapViewDelegate {
#IBOutlet weak var map: MKMapView!
let locationManager = CLLocationManager()
var events = Array<Event>()
var locations = Array<Location>()
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
locationManager.requestWhenInUseAuthorization()
locationManager.startUpdatingLocation()
locationManager.desiredAccuracy = kCLLocationAccuracyBest
// This closure gets called once for every event in your database
getEvents { (event, pin) in
self.tableView.reloadData()
if event != nil && pin != nil {
print(event!)
self.locations.append(pin!)
self.events.append(event!)
} else {
print("Failed to get event.")
}
}
}
func getEvents(results: #escaping (_ event: Event?, _ pin:Location?)->()) {
let ref = FIRDatabase.database().reference().child("Events")
ref.observe(.childAdded, with: { (snapshot) in
guard let value = snapshot.value as? Dictionary<String,String> else { return }
guard let name = value["eventName"],
let location = value["location"],
let attending = value["attendance"],
let dateTime = value["dateTime"],
let addedByUser = value["addedByUser"] else { return }
self.getEventPlacemark(address: location, results: { (placemark) in
if let placemark = placemark {
let pin = Location(title: name, coordinate: placemark.coordinate)
var distance: Double = -1 // If user location is not avalible, this will stay at -1
if let currentLocation = self.locationManager.location?.coordinate {
distance = pin.coordinate.distance(to: currentLocation)
}
let event = Event(id: snapshot.key, name: name, location: location, dateTime: dateTime, addedByUser: addedByUser, attending: attending, distance: distance)
results(event, pin)
return
}
})
})
}
func getEventPlacemark(address:String, results: #escaping (_ placemark: MKPlacemark?)->()){
let geocoder = CLGeocoder()
geocoder.geocodeAddressString(address) { (placemarks, error) in
if let error = error {
print(error.localizedDescription)
results(nil)
}
if let placemark = placemarks?.first {
results(MKPlacemark(placemark: placemark))
}
}
}
func displayAllEvents(){
self.map.addAnnotations(self.locations)
}
func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
if let userLocation = annotation as? MKUserLocation {
let view = (mapView.dequeueReusableAnnotationView(withIdentifier: "userLocationPin") as? MKPinAnnotationView) ?? MKPinAnnotationView(annotation: userLocation, reuseIdentifier: "userLocationPin")
view.pinTintColor = .purple
view.canShowCallout = true
return view
}
if let pin = annotation as? MKPointAnnotation {
let view = (mapView.dequeueReusableAnnotationView(withIdentifier: "pin") as? MKPinAnnotationView) ?? MKPinAnnotationView(annotation: pin, reuseIdentifier: "pin")
view.pinTintColor = .red
view.canShowCallout = true
return view
}
return nil
}
}
class Location: NSObject, MKAnnotation {
var title: String?
var coordinate: CLLocationCoordinate2D
init(title: String, coordinate: CLLocationCoordinate2D) {
self.title = title
self.coordinate = coordinate
}
}
struct Event {
var name: String
var location: String
}
extension CLLocationCoordinate2D {
func distance(to: CLLocationCoordinate2D) -> CLLocationDistance {
return MKMetersBetweenMapPoints(MKMapPointForCoordinate(self), MKMapPointForCoordinate(to))
}
}
If you are going to implement my code above, you'll need to remove your code from
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation])
because you don't need to add the pin manually anymore.
Can you try putting this in your view did load function and not have anything else run. This should put a pin to the west of Africa.
Something to notice, if the coordinate is
CLLocationCoordinate2D(latitude: 0, longitude: 0), the pin appears
right down at Antartica on the date line, which is the bottom right of
the map. So if for some reason your coordinate is the default 0,0,
your pins might by sitting there.
let pin = MKPointAnnotation()
pin.title = "Null Island"
pin.coordinate = CLLocationCoordinate2DMake(0.000001, 0.000001)
self.map.addAnnotation(pin)
This could possibly be where your pins are.