I am trying to build an app that shows some areas(polygons/overlays) on the map and when a polygon is tapped I would like to print on console print("Polygon \(zone_id) has been tapped"). The polygons are rendered from a GeoJSON file where we can also find the zone_id in the properties feature. So far I rendered the overlays on the map but I am stuck and I appreciate some guidance where to go from here.
I will paste my code that I have so far and also a snippet of the GeoJSON file.
import SwiftUI
import CoreLocation
struct Home: View {
@StateObject var mapData = MapViewModel()
var body: some View {
ZStack{
MapView()
.environmentObject(mapData)
.ignoresSafeArea(.all, edges: .all)
}
}
}
struct Home_Previews: PreviewProvider {
static var previews: some View {
Home()
}
}
import SwiftUI
import MapKit
struct MapView: UIViewRepresentable {
@EnvironmentObject var mapData: MapViewModel
@State var restrictions: [MKOverlay] = []
func makeCoordinator() -> Coordinator {
return MapView.Coordinator()
}
func makeUIView(context: Context) -> MKMapView {
let view = mapData.mapView
view.showsUserLocation = true
view.delegate = context.coordinator
mapData.showRestrictedZones { (restrictions) in
self.restrictions = restrictions
view.addOverlays(self.restrictions)
}
return view
}
func updateUIView(_ uiView: MKMapView, context: Context) {
}
class Coordinator: NSObject, MKMapViewDelegate {
func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
if let polygon = overlay as? MKPolygon {
let renderer = MKPolygonRenderer(polygon: polygon)
renderer.fillColor = UIColor.purple.withAlphaComponent(0.2)
renderer.strokeColor = .purple.withAlphaComponent(0.7)
return renderer
}
return MKOverlayRenderer(overlay: overlay)
}
}
}
import SwiftUI
import MapKit
// All Map Data Goes here...
class MapViewModel: NSObject, ObservableObject {
@Published var mapView = MKMapView()
// Decode GeoJSON from the server
func showRestrictedZones(completion: @escaping ([MKOverlay]) -> ()) {
guard let url = URL(string: "https://flightplan.romatsa.ro/init/static/zone_restrictionate_uav.json") else {
fatalError("Unable to get geoJSON") }
downloadData(fromURL: url) { (returnedData) in
if let data = returnedData {
var geoJson = [MKGeoJSONObject]()
do {
geoJson = try MKGeoJSONDecoder().decode(data)
} catch {
fatalError("Unable to decode GeoJSON")
}
var overlays = [MKOverlay]()
for item in geoJson {
if let feature = item as? MKGeoJSONFeature {
for geo in feature.geometry {
if let polygon = geo as? MKPolygon {
overlays.append(polygon)
}
}
}
}
DispatchQueue.main.async {
completion(overlays)
}
}
}
}
func downloadData( fromURL url: URL, completion: @escaping (_ data: Data?) -> ()) {
URLSession.shared.dataTask(with: url) { (data, response, error) in
guard
let data = data,
error == nil,
let response = response as? HTTPURLResponse,
response.statusCode >= 200 && response.statusCode < 300 else {
print("Error downloading data.")
completion(nil)
return
}
completion(data)
}
.resume()
}
}
And here is a snippet of the GeoJSON structure
{
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"id": "zone_restrictionate_uav.2120",
"geometry": {
"type": "Polygon",
"coordinates": [
[
[
24.98812963,
44.10877275
],
[
24.98806588,
44.1070722
],
[
24.98537796,
44.10717296
],
[
24.9854417,
44.10887351
],
[
24.98812963,
44.10877275
]
]
]
},
"geometry_name": "the_geom",
"properties": {
"zone_id": "RZ 2120",
"human_readable_definition": "POLYGON: 440631.5819N 0245917.2667E- 440625.4599N 0245917.0372E- 440625.8227N 0245907.3606E- 440631.9446N 0245907.5901E- 440631.5819N 0245917.2667E",
"wkt": "POLYGON((24.9881296281 44.1087727458,24.9880658794 44.1070721972,24.9853779561 44.1071729596,24.9854417047 44.1088735083,24.9881296281 44.1087727458))",
"lower_lim": "GND",
"upper_lim": "120m AGL",
"contact": "mailto: aerofoto@mapn.ro",
"status": "RESTRICTED"
}
},
{
"type": "Feature",
"id": "zone_restrictionate_uav.2121",
"geometry": {
"type": "Polygon",
"coordinates": [
[
[
26.44760265,
44.13453494
],
[
26.43440247,
44.11089351
],
[
26.38955244,
44.1359355
],
[
26.40275262,
44.15957693
],
[
26.44760265,
44.13453494
]
]
]
},
"geometry_name": "the_geom",
"properties": {
"zone_id": "RZ 2121",
"human_readable_definition": "POLYGON: 440804.3258N 0262651.3695E- 440639.2166N 0262603.8489E- 440809.3678N 0262322.3888E- 440934.4769N 0262409.9094E- 440804.3258N 0262651.3695E",
"wkt": "POLYGON((26.4476026463 44.1345349397,26.4344024672 44.1108935127,26.3895524427 44.1359355018,26.4027526218 44.1595769288,26.4476026463 44.1345349397))",
"lower_lim": "GND",
"upper_lim": "120m AGL",
"contact": "mailto: aerofoto@mapn.ro",
"status": "RESTRICTED"
}
}
],
"totalFeatures": 339,
"numberMatched": 339,
"numberReturned": 339,
"timeStamp": "2021-08-15T11:39:26.055Z"
}