Add WFS layer

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
// 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

@MainActor
struct AddWFSLayerView: View {
    /// A map with a topographic basemap centered on downtown Seattle.
    @State private var map: Map = {
        let map = Map(basemapStyle: .arcGISTopographic)
        map.initialViewpoint = Viewpoint(
            boundingGeometry: Envelope(
                xRange: -122.341581 ... -122.332662,
                yRange: 47.613758...47.617207,
                spatialReference: .wgs84
            )
        )

        let featureTable = WFSFeatureTable(url: .downtownSeattle, tableName: "Seattle_Downtown_Features:Buildings")
        // Sets the feature request mode to manual. In this mode, the table must be populated
        // manually. Panning and zooming won't request features automatically.
        featureTable.featureRequestMode = .manualCache
        // Sets the axis order.
        featureTable.axisOrder = .noSwap

        let wfsFeatureLayer = FeatureLayer(featureTable: featureTable)
        wfsFeatureLayer.renderer = SimpleRenderer(
            symbol: SimpleLineSymbol(
                style: .solid,
                color: .red,
                width: 3
            )
        )
        map.addOperationalLayer(wfsFeatureLayer)

        return map
    }()

    /// The visible area on the map.
    @State private var visibleArea: ArcGIS.Polygon?

    /// A feature table of building footprints for downtown Seattle.
    private var featureTable: WFSFeatureTable {
        (map.operationalLayers[0] as! FeatureLayer).featureTable as! WFSFeatureTable
    }

    /// The extent with which to populate the WFS layer.
    @State private var populateExtent: Envelope?

    /// A Boolean value indicating whether the feature table is being populated.
    @State private var isPopulating = false

    /// The error shown in the error alert.
    @State private var error: Error?

    var body: some View {
        MapView(map: map)
            .onVisibleAreaChanged {
                if visibleArea == nil {
                    // Populate the initial extent.
                    populateExtent = $0.extent
                }
                // Update visible area state.
                visibleArea = $0
            }
            .onNavigatingChanged { isNavigating in
                if !isNavigating {
                    // Populate when the user stops navigating.
                    populateExtent = visibleArea?.extent
                }
            }
            .task(id: populateExtent) {
                do {
                    guard let populateExtent else { return }
                    try await populateFeatures(within: populateExtent)
                } catch {
                    self.error = error
                }
            }
            .overlay(alignment: .center) {
                if isPopulating {
                    VStack {
                        Text("Populating")
                        ProgressView()
                            .progressViewStyle(.circular)
                    }
                    .padding()
                    .background(.ultraThickMaterial)
                    .clipShape(.rect(cornerRadius: 10))
                    .shadow(radius: 50)
                }
            }
            .errorAlert(presentingError: $error)
    }

    /// Populates the feature table using queried features contained within a given extent.
    /// - Parameter extent: The extent used to filter the results.
    private func populateFeatures(within extent: Envelope) async throws {
        isPopulating = true
        defer { isPopulating = false }

        let queryParameters = QueryParameters()
        queryParameters.geometry = extent
        queryParameters.spatialRelationship = .intersects
        _ = try await featureTable.populateFromService(
            using: queryParameters,
            clearCache: false,
            outFields: []
        )
    }
}

private extension URL {
    /// Downtown Seattle feature service URL used to create a feature layer.
    static var downtownSeattle: URL {
        URL(string: "https://dservices2.arcgis.com/ZQgQTuoyBrtmoGdP/arcgis/services/Seattle_Downtown_Features/WFSServer?service=wfs&request=getcapabilities")!
    }
}

#Preview {
    AddWFSLayerView()
}