Query features with Arcade expression

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 // 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 ArcGIS import SwiftUI  struct QueryFeaturesWithArcadeExpressionView: View {  /// The view model for the sample.  @StateObject private var model = Model()   /// The point on the screen where the user tapped.  @State private var tapScreenPoint: CGPoint?   /// The placement of the callout on the map.  @State private var calloutPlacement: CalloutPlacement?   /// The error shown in the error alert.  @State private var error: Error?   var body: some View {  MapViewReader { mapViewProxy in  MapView(map: model.map)  .callout(placement: $calloutPlacement.animation(.default.speed(2))) { placement in  let crimeCount = placement.geoElement?.attributes["Crime_Count"] as! Int  Text("Crimes in the last 60 days: \(crimeCount)")  .font(.callout)  .padding(8)  }  .onSingleTapGesture { screenPoint, _ in  tapScreenPoint = screenPoint  }  .task(id: tapScreenPoint) {  guard let tapScreenPoint else { return }  calloutPlacement = nil   do {  // Identify the tapped feature using the map view proxy.  let identifyResults = try await mapViewProxy.identifyLayers(  screenPoint: tapScreenPoint,  tolerance: 10  )   guard let identifiedGeoElements = identifyResults.first?.geoElements,  let identifiedFeature = identifiedGeoElements.first as? ArcGISFeature,  let tapMapPoint = mapViewProxy.location(fromScreenPoint: tapScreenPoint)  else { return }   // Evaluate the crime count for the feature.  let crimeCount = try await model.crimeCount(for: identifiedFeature)   // Update the callout with the evaluation results.  identifiedFeature.setAttributeValue(crimeCount, forKey: "Crime_Count")  calloutPlacement = .geoElement(identifiedFeature, tapLocation: tapMapPoint)   await mapViewProxy.setViewpointCenter(tapMapPoint)  } catch {  self.error = error  }  }  .overlay(alignment: .center) {  if model.isEvaluating {  VStack {  Text("Evaluating")  ProgressView()  .progressViewStyle(.circular)  }  .padding()  .background(.ultraThickMaterial)  .clipShape(.rect(cornerRadius: 10))  .shadow(radius: 50)  }  }  .task {  await mapViewProxy.setViewpointScale(2e5)  }  .errorAlert(presentingError: $error)  }  } }  private extension QueryFeaturesWithArcadeExpressionView {  /// The view model for the sample.  @MainActor  class Model: ObservableObject {  /// A map of the "Crime in Police Beats" portal item.  let map: Map = {  // Create a portal item using a portal and item ID.  let portalItem = PortalItem(  portal: .arcGISOnline(connection: .anonymous),  id: .crimesInPoliceBeats  )   // Create a map using the portal item.  let map = Map(item: portalItem)  return map  }()   /// The Arcade evaluator for evaluating the crime count of a feature.  private let crimeCountEvaluator: ArcadeEvaluator = {  // Create a string containing the Arcade expression.  let expressionValue = """  var crimes = FeatureSetByName($map, 'Crime in the last 60 days');  return Count(Intersects($feature, crimes));  """   // Create an Arcade expression using the string.  let expression = ArcadeExpression(expression: expressionValue)   // Create an Arcade evaluator with the Arcade expression and an Arcade profile.  let evaluator = ArcadeEvaluator(expression: expression, profile: .formCalculation)  return evaluator  }()   /// A Boolean value indicating whether there is a current evaluation operation.  @Published private(set) var isEvaluating = false   /// Evaluates the crime count for a given feature.  /// - Parameter feature: The ArcGIS feature evaluate.  /// - Returns: The evaluated crime count in the last 60 days.  func crimeCount(for feature: ArcGISFeature) async throws -> Int {  isEvaluating = true  defer { isEvaluating = false }   // Create the profile variables for the script with the feature and map.  let profileVariables: [String: any Sendable] = ["$feature": feature, "$map": map]   // Evaluate for the profile variables using the evaluator.  let result = try await crimeCountEvaluator.evaluate(withProfileVariables: profileVariables)   // Cast the result to get it's value.  let crimeCount = result.result(as: .double) as? Double ?? 0  return Int(crimeCount)  }  } }  private extension PortalItem.ID {  /// The ID used in the "Crimes in Police Beats" portal item.  static var crimesInPoliceBeats: Self {  Self("539d93de54c7422f88f69bfac2aebf7d")!  } }  #Preview {  QueryFeaturesWithArcadeExpressionView() }