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I added multiple MKPolyline to a MKMapView. It looks fine on the beginning, but when I start zooming, the border of the MKPolyline gets lost on some poly lines.
zoomed out:
zoomed in:
here is the code I used:
import MapKit
import UIKit
class ViewController: UIViewController {
@IBOutlet weak var mapView: MKMapView!
override func viewDidLoad() {
super.viewDidLoad()
mapView.delegate = self
mapView.mapType = .mutedStandard
mapView.pointOfInterestFilter = .excludingAll
let tiles = [
MapTile(x: 8586, y: 5514),
MapTile(x: 8587, y: 5514),
MapTile(x: 8588, y: 5514),
MapTile(x: 8587, y: 5515),
]
let polygons = tiles.map { tile in
MKPolygon(coordinates: tile.locations, count: tile.locations.count)
}
mapView.addOverlays(polygons, level: .aboveLabels)
}
}
extension ViewController: MKMapViewDelegate {
func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
if let mapTile = overlay as? MKPolygon {
let renderer = MKPolygonRenderer(polygon: mapTile)
renderer.fillColor = .systemBlue.withAlphaComponent(0.15)
renderer.strokeColor = .systemBlue
renderer.lineWidth = 0.7
return renderer
}
return MKOverlayRenderer(overlay: overlay)
}
}
struct MapTile: Identifiable, Hashable {
let x: Int
let y: Int
var id: String { "\(x)-\(y)" }
static let zoomFactor = Double(1 << 14)
static func locationOrigin(tileX: Int, tileY: Int) -> CLLocationCoordinate2D {
let lon = (Double(tileX) / MapTile.zoomFactor) * 360.0 - 180.0
let lat = atan( sinh (.pi - (Double(tileY) / MapTile.zoomFactor) * 2 * Double.pi)) * (180.0 / .pi)
return CLLocationCoordinate2D(latitude: lat, longitude: lon)
}
var locationOrigin: CLLocationCoordinate2D {
MapTile.locationOrigin(tileX: x, tileY: y)
}
var locations: [CLLocationCoordinate2D] {
let topLeft = locationOrigin
let topRight = MapTile.locationOrigin(tileX: x + 1, tileY: y)
let bottomRight = MapTile.locationOrigin(tileX: x + 1, tileY: y + 1)
let bottomLeft = MapTile.locationOrigin(tileX: x, tileY: y + 1)
return [
topLeft,
topRight,
bottomRight,
bottomLeft
]
}
}
any ideas why this happens?
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