Query map image sublayer

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 // Copyright 2025 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 ArcGIS import SwiftUI  struct QueryMapImageSublayerView: View {  /// The view model for this sample.  @State private var model = Model()   /// The current viewpoint of the map view.  @State private var viewpoint: Viewpoint? = .westernUSA   /// A Boolean value indicating whether there is an ongoing query operation.  @State private var isQuerying = false   /// The minimum population value in the text field.  @State private var minimumPopulation: Int?   /// The error shown in the error alert.  @State private var error: Error?   var body: some View {  MapView(map: model.map, viewpoint: viewpoint, graphicsOverlays: [model.graphicsOverlay])  .onViewpointChanged(kind: .boundingGeometry) { viewpoint = $0 }  .overlay(alignment: .top) {  LabeledContent("Minimum population") {  TextField("1,000,000", value: $minimumPopulation, format: .number)  .multilineTextAlignment(.trailing)  }  .padding(8)  .background(Color.primary.colorInvert())  .clipShape(.rect(cornerRadius: 5))  .shadow(radius: 50)  .padding()  }  .toolbar {  ToolbarItem(placement: .bottomBar) {  Button("Query") {  isQuerying = true  }  .disabled(isQuerying || minimumPopulation == nil || viewpoint == nil)  .task(id: isQuerying) {  guard isQuerying, let minimumPopulation, let viewpoint else {  return  }  defer { isQuerying = false }   do {  try await model.queryMapImageSublayers(  minimumPopulation: minimumPopulation,  geometry: viewpoint.targetGeometry  )  } catch {  self.error = error  }  }  }  }  .task {  // Sets up the sublayers when the sample appears.  do {  try await model.setUpMapImageSublayers()  } catch {  self.error = error  }  }  .errorAlert(presentingError: $error)  } }  /// The view model for this sample. @MainActor private final class Model {  /// A map with a streets basemap.  let map = Map(basemapStyle: .arcGISStreets)   /// The graphics overlay for the query result graphics.  let graphicsOverlay = GraphicsOverlay()   /// The map image sublayers to query.  private var mapImageSublayers: [ArcGISMapImageSublayer] = []   /// The sublayer names and corresponding symbol that will be used for the  /// layers' query result graphics.  private let sublayerGraphicSymbols: [String: Symbol] = {  let citiesSymbol = SimpleMarkerSymbol(style: .circle, color: .red, size: 16)   let countyOutline = SimpleLineSymbol(style: .dash, color: .cyan, width: 2)  let countySymbol = SimpleFillSymbol(style: .diagonalCross, color: .cyan, outline: countyOutline)   let darkCyan = UIColor(red: 0, green: 0.55, blue: 0.55, alpha: 1)  let stateOutline = SimpleLineSymbol(style: .solid, color: darkCyan, width: 6)  let stateSymbol = SimpleFillSymbol(style: .noFill, color: .cyan, outline: stateOutline)   return ["Cities": citiesSymbol, "Counties": countySymbol, "States": stateSymbol]  }()   /// Sets up the map image sublayers used by this sample.  func setUpMapImageSublayers() async throws {  // Creates a map image layer and adds it to the map.  let mapImageLayer = ArcGISMapImageLayer(url: .usaMapService)  map.addOperationalLayer(mapImageLayer)   // Loads the layer and its map image sublayers.  try await mapImageLayer.load()  await mapImageLayer.mapImageSublayers.load()   // Gets the sublayers containing the field we will be querying (POP2000).  mapImageSublayers = mapImageLayer.mapImageSublayers.filter { sublayer in  sublayer.table?.field(named: "POP2000") != nil  }  }   /// Queries the map image sublayers and adds graphics for the resulting features.  /// - Parameters:  /// - minimumPopulation: The minimum population a feature must have to be  /// included in the results.  /// - geometry: The geometry to query within.  func queryMapImageSublayers(minimumPopulation: Int, geometry: Geometry) async throws {  // Removes all the graphics to have a fresh start.  graphicsOverlay.removeAllGraphics()   // Creates parameters to query for features with a population greater than the minimum.  let queryParameters = QueryParameters()  queryParameters.whereClause = "POP2000 > \(minimumPopulation)"  queryParameters.geometry = geometry   await withThrowingTaskGroup(of: Void.self) { group in  for sublayer in mapImageSublayers {  group.addTask { [weak self] in  // Queries the sublayer's table using the parameters.  let result = try await sublayer.table!.queryFeatures(using: queryParameters)   // Creates a graphic for each feature in the result.  let symbol = self?.sublayerGraphicSymbols[sublayer.name]  let graphics = result.features().map { feature in  let graphic = Graphic(geometry: feature.geometry, symbol: symbol)  // Sets the Z-index for consistent draw order.  graphic.zIndex = -sublayer.id  return graphic  }   // Adds the graphics to the overlay.  self?.graphicsOverlay.addGraphics(graphics)  }  }  }  } }  private extension Viewpoint {  /// A viewpoint centered on the western United States.  static var westernUSA: Viewpoint {  .init(  boundingGeometry: Envelope(  xRange: -13_933_000 ... -12_071_000,  yRange: 3_387_000 ... 6_701_000,  spatialReference: .webMercator  )  )  } }  private extension URL {  /// A web URL to a "USA" map server containing sample data for the United States.  static var usaMapService: URL {  URL(string: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/USA/MapServer")!  } }  #Preview {  QueryMapImageSublayerView() }