Apply class breaks renderer to sublayer

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// 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 ApplyClassBreaksRendererToSublayerView: View {
    /// The map image layer.
    @State private var mapImageLayer = ArcGISMapImageLayer(url: URL(string: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/Census/MapServer")!)

    /// The counties sublayer.
    @State private var countiesSublayer: ArcGISMapImageSublayer?

    /// The original renderer used to symbolize the sublayer.
    @State private var originalRenderer: Renderer?

    /// A Boolean value indicating that the class breaks renderer is applied.
    @State private var classBreaksRendererIsApplied = false

    /// The map with a topographic basemap style.
    @State private var map: Map = {
        let map = Map(basemapStyle: .arcGISTopographic)

        // Sets the initial viewpoint.
        map.initialViewpoint = Viewpoint(
            boundingGeometry: Envelope(
                xMin: -13934661.666904,
                yMin: 331181.323482,
                xMax: -7355704.998713,
                yMax: 9118038.075882,
                spatialReference: .webMercator
            )
        )
        return map
    }()

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

    var body: some View {
        MapView(map: map)
            .task {
                // Adds the map image layer to the map.
                map.addOperationalLayer(mapImageLayer)
                do {
                    // Loads the map image layer.
                    try await mapImageLayer.load()
                    // Gets the sublayers.
                    let mapImageSublayers = mapImageLayer.mapImageSublayers
                    // Gets the third sublayer.
                    let sublayer = mapImageSublayers[2]
                    // Loads the sublayer.
                    try await sublayer.load()
                    countiesSublayer = sublayer
                    originalRenderer = sublayer.renderer
                } catch {
                    self.error = error
                }
            }
            .toolbar {
                ToolbarItem(placement: .bottomBar) {
                    Toggle("Change Sublayer Renderer", isOn: $classBreaksRendererIsApplied)
                        .disabled(countiesSublayer == nil)
                }
            }
            .onChange(of: classBreaksRendererIsApplied) {
                countiesSublayer?.renderer = if classBreaksRendererIsApplied {
                    // Applies the class breaks renderer.
                    .populationRenderer
                } else {
                    // Applies the original renderer.
                    originalRenderer
                }
            }
            .errorAlert(presentingError: $error)
    }
}

private extension Renderer {
    /// Creates a class breaks renderer for counties in the US based on their
    /// population in 2007.
    static var populationRenderer: ClassBreaksRenderer {
        // Outline symbol.
        let lineSymbol = SimpleLineSymbol(style: .solid, color: UIColor(white: 0.6, alpha: 1), width: 0.5)

        // Symbol for each class break.
        let symbol1 = SimpleFillSymbol(style: .solid, color: UIColor(red: 0.89, green: 0.92, blue: 0.81, alpha: 1), outline: lineSymbol)
        let symbol2 = SimpleFillSymbol(style: .solid, color: UIColor(red: 0.59, green: 0.76, blue: 0.75, alpha: 1), outline: lineSymbol)
        let symbol3 = SimpleFillSymbol(style: .solid, color: UIColor(red: 0.38, green: 0.65, blue: 0.71, alpha: 1), outline: lineSymbol)
        let symbol4 = SimpleFillSymbol(style: .solid, color: UIColor(red: 0.27, green: 0.49, blue: 0.59, alpha: 1), outline: lineSymbol)
        let symbol5 = SimpleFillSymbol(style: .solid, color: UIColor(red: 0.16, green: 0.33, blue: 0.47, alpha: 1), outline: lineSymbol)

        // Class breaks.
        let classBreak1 = ClassBreak(description: "-99 to 8,560", label: "-99 to 8,560", minValue: -99, maxValue: 8_560, symbol: symbol1)
        let classBreak2 = ClassBreak(description: "> 8,560 to 18,109", label: "> 8,560 to 18,109", minValue: 8_561, maxValue: 18_109, symbol: symbol2)
        let classBreak3 = ClassBreak(description: "> 18,109 to 35,501", label: "> 18,109 to 35,501", minValue: 18_110, maxValue: 35_501, symbol: symbol3)
        let classBreak4 = ClassBreak(description: "> 35,501 to 86,100", label: "> 35,501 to 86,100", minValue: 35_502, maxValue: 86_100, symbol: symbol4)
        let classBreak5 = ClassBreak(description: "> 86,100 to 10,110,975", label: "> 86,100 to 10,110,975", minValue: 86_101, maxValue: 10_110_975, symbol: symbol5)

        return ClassBreaksRenderer(fieldName: "POP2007", classBreaks: [classBreak1, classBreak2, classBreak3, classBreak4, classBreak5])
    }
}

#Preview {
    ApplyClassBreaksRendererToSublayerView()
}