topic Re: Zoom to location in Swift Maps SDK Questions

Zoom to location

GBreen — Thu, 30 Mar 2023 13:33:39 GMT

I'm really liking the new SwiftUI implementation but I'm having trouble with one thing. I have a button to zoom to the current location. In order to do that I set a viewpoint and it works the first time. But if I move and try to tap it again it doesn't zoom. The workaround is I watch the viewpoint for changes and set it back to nil immediately. Is this the best way to implement zooming or is there some other way to do it? I can't find anything in the docs for it. Here's the example code:

struct MapZoomTestView: View { @StateObject private var map: Map = { let map = Map(basemapStyle: .arcGISTopographic) map.initialViewpoint = Viewpoint(latitude: 34.02700, longitude: -118.80500, scale: 72_000) return map }() @State var viewpoint: Viewpoint? = nil let locationDisplay = LocationDisplay(dataSource: SystemLocationDataSource()) init() { ArcGISEnvironment.apiKey = APIKey("") } var body: some View { MapView(map: map, viewpoint: viewpoint) .locationDisplay(locationDisplay) .task { let locationManager = CLLocationManager() if locationManager.authorizationStatus == .notDetermined { locationManager.requestWhenInUseAuthorization() } do { try await locationDisplay.dataSource.start() } catch { print("Current Location Cannot Be Shown") } } .overlay(alignment: .bottomLeading) { Button { guard let location = locationDisplay.location else { return } viewpoint = Viewpoint(center: location.position, scale: 10_000) } label: { Image(systemName: "paperplane.fill") } .frame(width: 50, height: 50, alignment: .center) .background(.regularMaterial) .cornerRadius(25.0) .padding([.leading, .bottom]) } .onChange(of: viewpoint) { newValue in guard newValue != nil else { return } viewpoint = nil } .ignoresSafeArea() } }

Re: Zoom to location

DuanePfeiffer — Thu, 30 Mar 2023 14:07:05 GMT

I accomplish this by setting the locationDisplay.autoPanMode. Not sure if that is your desired outcome or not.

appData.locationDisplay.autoPanMode = .recenter

Re: Zoom to location

GBreen — Thu, 30 Mar 2023 14:11:44 GMT

Yeah I thought about that too but then the map follows the user where I just want them to be able to decide when to zoom, not auto pan. I could do something like below but that seems just as hacky

locationDisplay.autoPanMode = .recenter locationDisplay.autoPanMode = .off

Re: Zoom to location

GBreen — Thu, 30 Mar 2023 14:12:52 GMT

Also I would like a solution that can be used to zoom to other geometries as well, not just the current location if that makes sense.

Re: Zoom to location

rolson_esri — Thu, 30 Mar 2023 14:48:46 GMT

What you have works with the beta release. As you have noticed, this isn't ideal. Final (200.1) should be released soon and there will be a much better way to achieve what you are looking for via a MapViewReader and the associated proxy:

var body: some View { MapViewReader { proxy in MapView(map: map, viewpoint: viewpoint) .locationDisplay(locationDisplay) .task { let locationManager = CLLocationManager() if locationManager.authorizationStatus == .notDetermined { locationManager.requestWhenInUseAuthorization() } do { try await locationDisplay.dataSource.start() } catch { print("Current Location Cannot Be Shown") } } .overlay(alignment: .bottomLeading) { Button { guard let location = locationDisplay.location else { return } Task { await proxy.setViewpointCenter(location.position, scale: 10_000) } } label: { Image(systemName: "paperplane.fill") } .frame(width: 50, height: 50, alignment: .center) .background(.regularMaterial) .cornerRadius(25.0) .padding([.leading, .bottom]) } .ignoresSafeArea() } }

Note: the call above that sets the viewpoint (`proxy.setViewpointCenter(:scale:)`) will actually animate to the new viewpoint. You can tell that because it's an async call. There will also be an un-animated setViewpoint function on the proxy once we release 200.1.

Re: Zoom to location

GBreen — Thu, 30 Mar 2023 14:48:08 GMT

Oh Awesome! I'm already using the MapViewReader for and identify operation so that will be super simple to implement. Thanks!

Re: Zoom to location

Ting — Wed, 19 Apr 2023 17:15:42 GMT

With the 200.1 release, we have a Change viewpoint sample that shows this API. 🙂