Specify a map’s spatial reference.

Use case
Choosing the correct spatial reference is important for ensuring accurate projection of data points to a map.
How to use the sample
Pan and zoom around the map. Observe how the map is displayed in the World Bonne spatial reference. Pick a different spatial reference and see the map reproject.
How it works
- Instantiate a
Mapobject using a spatial reference. - Instantiate a
Basemapobject using anArcGISMapImageLayerobject. - Set the basemap to the map.
- Set the map to a
MapViewobject. - Change the map’s spatial reference using
setSpatialReferencemethod.
The ArcGIS map image layer will reproject into the spatial reference set to the map (such as World Bonne (WKID: 54024)), and not the map service’s default spatial reference.
Relevant API
- ArcGISMapImageLayer
- Basemap
- Map
- MapView
- SpatialReference
About the data
This sample uses a World Cities Population map service that displays world cities symbolized based on population.
Additional information
Operational layers will automatically project to this spatial reference when possible. There are 3 kinds of layer reprojection behaviors:
- Reprojected on device (on-the-fly reprojection), such as a
FeatureLayercreated from a mobile geodatabase - Reprojected from the service, such as an
ArcGISMapImageLayer - Not able to reproject, such as an
ArcGISTiledLayerwith defined spatial reference in its tile cache. These layers might be able to reproject in a future update
For more information, check out the API reference doc for setSpatialReference method.
Tags
coordinate system, project, projection, spatial reference, Web Mercator, WGS84, WKID
Sample code
// Copyright 2024 Esri//// Licensed under the Apache License, Version 2.0 (the "License");// you may not use this file except in compliance with the License.// You may obtain a copy of the License at//// https://www.apache.org/licenses/LICENSE-2.0//// Unless required by applicable law or agreed to in writing, software// distributed under the License is distributed on an "AS IS" BASIS,// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.// See the License for the specific language governing permissions and// limitations under the License.
import ArcGISimport SwiftUI
struct SetSpatialReferenceView: View { /// A map with spatial reference and a basemap. @State private var map: Map = { let map = Map(spatialReference: .worldBonne) map.basemap = Basemap( baseLayer: ArcGISMapImageLayer(url: .worldCities) ) return map }() /// The currently selected spatial reference. @State private var selectedSpatialReference: SpatialReference = .worldBonne
var body: some View { MapView(map: map) .toolbar { ToolbarItem(placement: .bottomBar) { Picker("Spatial Reference", selection: $selectedSpatialReference) { ForEach(SpatialReference.allOptions, id: \.wkid) { spatialReference in Text(spatialReference.name) .tag(spatialReference) } } .onChange(of: selectedSpatialReference) { map.setSpatialReference(selectedSpatialReference) } .fixedSize() } } }}
private extension URL { /// The URL to the World Cities map service for the map image layer. static var worldCities: URL { URL(string: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/SampleWorldCities/MapServer")! }}
// MARK: - Spatial References
private extension SpatialReference { /// A human-readable name for the spatial reference. var name: String { switch self { case .berghausStar: "Berghaus Star AAG" case .fuller: "Fuller" case .newZealandMapGrid: "New Zealand Map Grid" case .northPoleStereographic: "North Pole Stereographic" case .peirceQuincuncial: "Peirce Quincuncial" case .utmZone10N: "UTM Zone 10 N" case .worldBonne: "World Bonne" case .worldOrthographic: "World Orthographic" case .worldGoodeHomolosine: "World Goode Homolosine" case .webMercator: "Web Mercator" case .wgs84: "WGS 84" default: "Unknown" } }
/// Berghaus Star AAG (WKID: 102299). static var berghausStar: SpatialReference { SpatialReference(wkid: WKID(102299)!)! } /// Fuller (WKID: 54050). static var fuller: SpatialReference { SpatialReference(wkid: WKID(54050)!)! } /// New Zealand Map Grid (WKID: 27200). static var newZealandMapGrid: SpatialReference { SpatialReference(wkid: WKID(27200)!)! } /// North Pole Stereographic (WKID: 102018). static var northPoleStereographic: SpatialReference { SpatialReference(wkid: WKID(102018)!)! } /// Peirce quincuncial North Pole in a square (WKID: 54090). static var peirceQuincuncial: SpatialReference { SpatialReference(wkid: WKID(54090)!)! } /// UTM Zone 10 N (WKID: 32610). static var utmZone10N: SpatialReference { SpatialReference(wkid: WKID(32610)!)! } /// World Bonne (WKID: 54024). static var worldBonne: SpatialReference { SpatialReference(wkid: WKID(54024)!)! } /// World Goode Homolosine Land (WKID: 54052). static var worldGoodeHomolosine: SpatialReference { SpatialReference(wkid: WKID(54052)!)! } /// Orthographic projection of the World from Space (WKID: 102038). static var worldOrthographic: SpatialReference { SpatialReference(wkid: WKID(102038)!)! }
/// All available spatial references for selection. static var allOptions: [SpatialReference] { return [ .berghausStar, .fuller, .newZealandMapGrid, .northPoleStereographic, .peirceQuincuncial, .utmZone10N, .worldBonne, .worldGoodeHomolosine, .worldOrthographic, .webMercator, .wgs84 ] }}
#Preview { SetSpatialReferenceView()}