Geojson performance

import UIKit
import MapboxMaps
 
final class LargeGeoJSONPerformanceExample: UIViewController, ExampleProtocol {
private static let largeSourceCount = 5
 
private var mapView: MapView!
private var geoJSON = ""
private var jsonUpdateCounter = 0
private var cancelables = Set<AnyCancelable>()
 
override func viewDidLoad() {
super.viewDidLoad()
 
mapView = MapView(frame: view.bounds)
mapView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
mapView.ornaments.options.scaleBar.visibility = .visible
 
view.addSubview(mapView)
 
let asset = NSDataAsset(name: "long_route")
geoJSON = String(data: asset!.data, encoding: .utf8)!
 
mapView.mapboxMap.onStyleLoaded.observeNext { [weak self] _ in
try! self?.setupExample()
}.store(in: &cancelables)
 
// Print updates when sources with added dataIds are updated
mapView.mapboxMap.onSourceDataLoaded.observe { event in
if let dataId = event.dataId {
print("GeoJsonSource was updated, data-id: \(dataId)")
}
}.store(in: &cancelables)
}
 
private func setupExample() throws {
let cameraCenter = CLLocationCoordinate2D(latitude: 51.1079, longitude: 17.0385)
let cameraOptions = CameraOptions(center: cameraCenter, zoom: 6)
mapView.mapboxMap.setCamera(to: cameraOptions)
 
mapView.camera.fly(to: CameraOptions(zoom: 2), duration: 10) { [weak self] _ in
// The below line is used for internal testing purposes only.
self?.finish()
}
 
for i in 0..<Self.largeSourceCount {
var source = GeoJSONSource(id: "source_\(i)")
source.data = .string(geoJSON)
 
var lineLayer = LineLayer(id: "line_layer_\(i)", source: source.id)
lineLayer.lineColor = .constant(StyleColor(.systemBlue))
lineLayer.lineOffset = .constant(Double(5 * i))
 
// Add the geoJSONSourceData with a dataId, which will be returned when that data source is updated
try mapView.mapboxMap.addSource(source, dataId: String(jsonUpdateCounter))
try mapView.mapboxMap.addLayer(lineLayer)
 
jsonUpdateCounter += 1
}
 
try mapView.mapboxMap.addImage(UIImage(named: "blue_marker_view")!, id: "icon")
 
var source = GeoJSONSource(id: "source_marker")
source.data = .feature(Feature(geometry: Point(cameraCenter).geometry))
 
// Add the geoJSONSourceData with a dataId, which will be returned when that data source is updated
try mapView.mapboxMap.addSource(source, dataId: String(jsonUpdateCounter))
jsonUpdateCounter += 1
 
var symbolLayer = SymbolLayer(id: "layer_marker", source: source.id)
symbolLayer.iconImage = .constant(.name("icon"))
symbolLayer.iconAnchor = .constant(.bottom)
 
try mapView.mapboxMap.addLayer(symbolLayer)
 
try loadAdditionalGeoJSON()
}
 
private func loadAdditionalGeoJSON() throws {
var source = GeoJSONSource(id: "source_\(Self.largeSourceCount)")
source.data = .string(geoJSON)
 
// Add the geoJSONSourceData with a dataId, which will be returned when that data source is updated
try mapView.mapboxMap.addSource(source, dataId: String(jsonUpdateCounter))
jsonUpdateCounter += 1
 
var lineLayer = LineLayer(id: "line_layer_\(Self.largeSourceCount)", source: source.id)
lineLayer.lineColor = .constant(StyleColor(.systemGreen))
lineLayer.lineOffset = .constant(Double(5 * Self.largeSourceCount))
 
try mapView.mapboxMap.addLayer(lineLayer)
}
}