3

I am able to draw the polygon on mapView however I need to locate the polygon and zoom it manually. Is there a way to do this process automatically like adjust the polygon in centre? I have browsed the internet and read few related articles, most of them are based on polylines and points. Any kind of help will be appreciated, as I am finding for the solution for a while. Thanks in advance.

Using the following methods to draw the polygon on mapView : -

func drawFence(coordinates: UnsafePointer<CLLocationCoordinate2D>, count: Int) {
        let makePoly = MKPolygon(coordinates: coordinates, count: count)
        mapview.addOverlay(makePoly)
    }

func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
    guard let polyOverlay = overlay as? MKPolygon else { return MKOverlayRenderer() }
    let polyRender = MKPolygonRenderer(polygon: polyOverlay)
    polyRender.fillColor = #colorLiteral(red: 0.9764705882, green: 0.09803921569, blue: 0.2588235294, alpha: 0.6)
    polyRender.strokeColor = #colorLiteral(red: 0.9764705882, green: 0.09803921569, blue: 0.2588235294, alpha: 1)
    polyRender.lineWidth = 2
    return polyRender
}
Saurabh
  • 745
  • 1
  • 9
  • 33
  • try this will zoom/pan to fit all overlays with a little buffer : if let first = mapView.overlays.first { let rect = mapView.overlays.reduce(first.boundingMapRect, combine: {MKMapRectUnion($0, $1.boundingMapRect)}) mapView.setVisibleMapRect(rect, edgePadding: UIEdgeInsets(top: 50.0, left: 50.0, bottom: 50.0, right: 50.0), animated: true) } – Dhaval Raval Nov 05 '19 at 09:22
  • @DhavalRaval i have tried this code before, and there is no property called "MKMapRectUnion" – Saurabh Nov 05 '19 at 09:28
  • @Rob thanks, the title suggested by you makes sense, I have changed it accordingly. – Saurabh Nov 07 '19 at 04:49

1 Answers1

6

If you’re trying to zoom into a particular overlay, you can:

let insets = UIEdgeInsets(top: 50, left: 50, bottom: 50, right: 50)

func zoom(for overlay: MKOverlay) {
    mapView.setVisibleMapRect(overlay.boundingMapRect, edgePadding: insets, animated: true)
}

enter image description here

If you want to zoom the map to show all the overlays, you can do:

func zoomForAllOverlays() {
    guard let initial = mapView.overlays.first?.boundingMapRect else { return }

    let mapRect = mapView.overlays
        .dropFirst()
        .reduce(initial) { $0.union($1.boundingMapRect) }

    mapView.setVisibleMapRect(mapRect, edgePadding: insets, animated: true)
}

For example, having added two overlays (over NYC and Stamford), I called that routine, and it resulted in:

mapview w two overlays

By the way, I know the question was about Polygon overlays, but the technique works regardless of the overlay type. It was just simpler to create Circle overlays for demonstration purposes.

Rob
  • 415,655
  • 72
  • 787
  • 1,044
  • 1
    I have made the necessary code changes as mentioned, and it worked like a charm for both the overlays. – Saurabh Nov 07 '19 at 04:57
  • 1
    I am calling zoomForAllOverlays() in - (void)mapViewWillStartRenderingMap:(MKMapView *)mapView and it works well. – p-mercier Jun 08 '22 at 14:44