Create symbol styles from web styles

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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 // Copyright 2023 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 CreateSymbolStylesFromWebStylesView: View {  /// The display scale of the environment.  @Environment(\.displayScale) private var displayScale   /// A map with a light gray basemap centered on LA County.  @State private var map: Map = {  let map = Map(basemapStyle: .arcGISLightGray)  map.referenceScale = 1e5  map.initialViewpoint = Viewpoint(  latitude: 34.28301,  longitude: -118.44186,  scale: 1e4  )  return map  }()   /// A feature layer with the LA County Points of Interest service.  @State private var featureLayer: FeatureLayer = {  let featureTable = ServiceFeatureTable(url: .laPointsOfInterest)  return FeatureLayer(featureTable: featureTable)  }()   /// The legend items for the different symbols from the selected symbol style.  @State private var legendItems: [LegendItem] = []   /// A Boolean value indicating whether the legend sheet is showing.  @State private var isShowingLegend = false   var body: some View {  MapView(map: map)  .onScaleChanged { scale in  // Prevent the symbols from scaling when the map zooms out too far.  featureLayer.scalesSymbols = scale >= 8e4  }  .task(id: displayScale) {  // Update the symbols when the display scale changes.  await updateSymbols(displayScale: displayScale)  }  .toolbar {  ToolbarItem(placement: .bottomBar) {  Button("Legend") {  isShowingLegend = true  }  .popover(isPresented: $isShowingLegend) {  NavigationStack {  LegendList(legendItems: $legendItems)  .navigationTitle("Symbol Styles")  .navigationBarTitleDisplayMode(.inline)  .toolbar {  ToolbarItem(placement: .confirmationAction) {  Button("Done") {  isShowingLegend = false  }  }  }  }  .presentationDetents([.fraction(0.5)])  .frame(idealWidth: 320, idealHeight: 380)  }  }  }  }   /// The legend list that describes what each symbol represents.  private struct LegendList: View {  /// A binding to the list of legend items to show.  @Binding var legendItems: [LegendItem]   var body: some View {  List(legendItems, id: \.name) { legendItem in  Label {  Text(legendItem.name)  } icon: {  Image(uiImage: legendItem.image)  }  }  }  } }  private extension CreateSymbolStylesFromWebStylesView {  /// Updates the symbols using the symbol style.  /// - Parameter scale: The display scale for the swatch images.  private func updateSymbols(displayScale: CGFloat) async {  // An Esri 2D point symbol style created from a web style.  let esri2DPointSymbolStyle = SymbolStyle(  styleName: "Esri2DPointSymbolsStyle",  portal: .arcGISOnline(connection: .anonymous)  )   // Get the symbols and associated information using the symbol style and types.  let symbolDetails = await getSymbols(  symbolStyle: esri2DPointSymbolStyle,  symbolTypes: SymbolType.allCases  )   // Create the legend list with symbol swatches and related details.  let legendItems: [LegendItem] = await withTaskGroup(of: LegendItem?.self) { group in  for detail in symbolDetails {  group.addTask {  // Get the image swatch for the symbol using the display scale.  if let swatch = try? await detail.symbol.makeSwatch(scale: displayScale) {  return LegendItem(name: detail.name, image: swatch)  } else {  return nil  }  }  }   var items: [LegendItem] = []  for await legendItem in group where legendItem != nil {  items.append(legendItem!)  }  return items  }   // Update the legend list items.  self.legendItems = legendItems.sorted(using: KeyPathComparator(\.name))   // Create unique values and set them to the feature layer's renderer.  featureLayer.renderer = makeUniqueValueRenderer(fieldNames: ["cat2"], symbolDetails: symbolDetails)   // Add the feature layer with updated symbols to the map.  map.removeAllOperationalLayers()  map.addOperationalLayer(featureLayer)  }   /// Get certain types of symbols from a symbol style.  /// - Parameters:  /// - symbolStyle: A `SymbolStyle` object from a web style.  /// - symbolTypes: The types of symbols to get from the symbol style.  /// - Returns: An `Array` of `SymbolDetail`s which contain a symbol and associated information.  private func getSymbols(symbolStyle: SymbolStyle, symbolTypes: [SymbolType]) async -> [SymbolDetail] {  // Get the symbol and details for each symbol type.  let symbolDetails: [SymbolDetail] = await withTaskGroup(of: [SymbolDetail]?.self) { group in  for type in symbolTypes {  group.addTask {  // Get the symbol from the symbol style using the symbol's name from the type.  async let symbol = symbolStyle.symbol(forKeys: [type.name])  if let symbolDetail = try? await [SymbolDetail(  name: type.name,  categoryNames: type.categoryNames,  symbol: symbol  )] {  return symbolDetail  } else {  return nil  }  }  }   var details: [SymbolDetail] = []  for await detail in group where detail != nil {  details.append(contentsOf: detail!)  }  return details  }  return symbolDetails  }   /// Creates a `UniqueValueRenderer` used to render a feature layer with symbol styles.  /// - Parameters:  /// - fieldNames: The attributes to match the unique values against.  /// - symbolDetails: An `Array` of symbols and their associated information.  /// - Returns: An `UniqueValueRenderer` object with the symbol `UniqueValue`s.  private func makeUniqueValueRenderer(fieldNames: [String], symbolDetails: [SymbolDetail]) -> UniqueValueRenderer {  let uniqueValues = symbolDetails.flatMap { detail in  // Create a unique value for each category value of symbol so the  // field name matches to all category values.  detail.categoryNames.map { value in  UniqueValue(description: "", label: detail.name, symbol: detail.symbol, values: [value])  }  }  return UniqueValueRenderer(fieldNames: fieldNames, uniqueValues: uniqueValues)  }   /// A struct containing a symbol and its associated information.  private struct SymbolDetail {  /// The name of the symbol in the web style.  let name: String  /// The category names of features represented by the symbol.  let categoryNames: [String]  /// The symbol from the symbol style.  let symbol: Symbol  }   /// A struct for displaying legend info in a list row.  private struct LegendItem {  /// The description label of the legend item.  let name: String  /// The image swatch of the legend item.  let image: UIImage  }   /// The types of symbols to get from the symbol style.  private enum SymbolType: CaseIterable, Comparable {  case atm, beach, campground, cityHall, hospital, library, park, placeOfWorship, policeStation, postOffice, school, trail   /// The names of the symbols in the web style.  var name: String {  switch self {  case .atm:  return "atm"  case .beach:  return "beach"  case .campground:  return "campground"  case .cityHall:  return "city-hall"  case .hospital:  return "hospital"  case .library:  return "library"  case .park:  return "park"  case .placeOfWorship:  return "place-of-worship"  case .policeStation:  return "police-station"  case .postOffice:  return "post-office"  case .school:  return "school"  case .trail:  return "trail"  }  }   /// The category names of features represented by a type of symbol.  var categoryNames: [String] {  switch self {  case .atm:  return ["Banking and Finance"]  case .beach:  return ["Beaches and Marinas"]  case .campground:  return ["Campgrounds"]  case .cityHall:  return ["City Halls", "Government Offices"]  case .hospital:  return ["Hospitals and Medical Centers", "Health Screening and Testing", "Health Centers", "Mental Health Centers"]  case .library:  return ["Libraries"]  case .park:  return ["Parks and Gardens"]  case .placeOfWorship:  return ["Churches"]  case .policeStation:  return ["Sheriff and Police Stations"]  case .postOffice:  return ["DHL Locations", "Federal Express Locations"]  case .school:  return ["Public High Schools", "Public Elementary Schools", "Private and Charter Schools"]  case .trail:  return ["Trails"]  }  }  } }  private extension URL {  /// LA County Points of Interest service URL used to create a feature layer.  static var laPointsOfInterest: URL {  URL(string: "http://services.arcgis.com/V6ZHFr6zdgNZuVG0/arcgis/rest/services/LA_County_Points_of_Interest/FeatureServer/0")!  } }  #Preview {  NavigationStack {  CreateSymbolStylesFromWebStylesView()  } }