How to create multiple MapKit annotations by using data from a server? - ios

Question

I have been having a real tough time making multiple annotations on a MapView. So far I have been able to create the relevant classes to download, parse and store the data into an array that can be used. Yet I am still struggling to use the said data and make the annotations required.
HomeModel Class - download and parse the required information from the server
import UIKit
import Foundation
protocol HomeModelProtocol: class {
func itemsDownloaded(items: NSArray)
}
class HomeModel: NSObject, URLSessionDataDelegate {
weak var delegate: HomeModelProtocol!
var data = Data()
let urlPath: String = "https://FAKEDATABASEURL.XYZ"
func downloadItems() {
let url: URL = URL(string: urlPath)!
let defaultSession = Foundation.URLSession(configuration: URLSessionConfiguration.default)
let task = defaultSession.dataTask(with: url) { (data, response, error) in
if error != nil {
print("Failed to download data")
} else {
print("Data downloaded")
self.parseJSON(data!)
}
}
task.resume()
}
func parseJSON(_ data:Data) {
var jsonResult = NSArray()
do {
jsonResult = try JSONSerialization.jsonObject(with: data, options: JSONSerialization.ReadingOptions.allowFragments) as! NSArray
} catch let error as NSError {
print(error)
}
var jsonElement = NSDictionary()
let locations = NSMutableArray()
for i in 0 ..< jsonResult.count {
jsonElement = jsonResult[i] as! NSDictionary
let location = LocationModel()
if let name = jsonElement["Name"] as? String,
let address = jsonElement["Address"] as? String,
let latitude = jsonElement["Latitude"] as? String,
let longitude = jsonElement["Longitude"] as? String {
location.name = name
location.address = address
location.latitude = latitude
location.longitude = longitude
}
locations.add(location)
}
DispatchQueue.main.async(execute: { ()-> Void in
self.delegate.itemsDownloaded(items: locations)
})
}
}
LocalModel Class - To store the data into an array to be used by the app
import UIKit
import Foundation
class LocationModel: NSObject {
// Properties
var name: String?
var address: String?
var latitude: String?
var longitude: String?
// Empty constructor
override init() { }
// Construct with #name, #address, #latitude and #longitude.
init(name: String, address: String, latitude: String, longitude: String) {
self.name = name
self.address = address
self.latitude = latitude
self.longitude = longitude
}
// Print the object's current state
override var description: String {
return "Name: \(String(describing: name)), Address:\(String(describing: address)), Latitude: \(String(describing: latitude)), Longitude: \(String(describing: longitude))"
}
}
Map View Controller - Controls the map for the application
import UIKit
import MapKit
import CoreLocation
class HotPlacesViewController: UIViewController, CLLocationManagerDelegate, MKMapViewDelegate {
#IBOutlet weak var mapView: MKMapView!
var isFirstTime = true
var locationManager = CLLocationManager()
let newPin = MKPointAnnotation()
var selectedLocation:LocationModel?
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
// Setup the location services delegate in this class.
locationManager.delegate = self
// This little method requests the users permission for location services whilst in this view controller.
if CLLocationManager.authorizationStatus() == .notDetermined {
self.locationManager.requestAlwaysAuthorization()
let alert = UIAlertController(title: "You can change this option in the Settings App", message: "So keep calm your selection is not permanent. 🙂",
preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
self.present(alert, animated: true, completion: nil)
}
locationManager.distanceFilter = kCLDistanceFilterNone
locationManager.desiredAccuracy = kCLLocationAccuracyBest
locationManager.startUpdatingLocation()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
}
// Drops the pin on the users current location.
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
mapView.removeAnnotation(newPin)
let location = locations.last! as CLLocation
let center = CLLocationCoordinate2D(latitude: location.coordinate.latitude, longitude: location.coordinate.longitude)
if(self.isFirstTime) {
let region = MKCoordinateRegion(center: center, span: MKCoordinateSpan(latitudeDelta: 0.01, longitudeDelta: 0.01))
// Set the region on the map.
mapView.setRegion(region, animated: true)
self.isFirstTime = false
}
newPin.coordinate = location.coordinate
mapView.addAnnotation(newPin)
}
}

Answer 1

Make your let locations = NSMutableArray() array accessible by other classes so that you can use this array in your HotPlacesViewController class.
Then in your HotPlacesViewController class declare a property for holding locations data. And load the data inside viewDidLoad() like:
class HotPlacesViewController: UIViewController, CLLocationManagerDelegate, MKMapViewDelegate {
// declare a property which will hold the locations data
override func viewDidLoad() {
...
...
locations = // load your data here
}
}
Then, for multiple annotations follow this logic:
for location in locations {
let annotation = MKPointAnnotation()
annotation.title = location.name
annotation.coordinate = CLLocationCoordinate2D(latitude: location.latitude, longitude: location.longitude)
mapView.addAnnotation(annotation)
}