topic Swift Layer List Examples in Swift Maps SDK Questions

Swift Layer List Examples

Justin_Greco — Thu, 06 Apr 2023 12:36:02 GMT

Are there any examples of building a layer list from a web map, particularly one with group layers? I am get the layers from map.operationalLayers to show in a List view, but am struggling with getting the sublayer for group layers to appear as children, since the . The layer list is not part of the toolkit, are there plans to have add one in the future?

Re: Swift Layer List Examples

Justin_Greco — Thu, 06 Apr 2023 14:30:18 GMT

Was a bit easier than I had thought. Here is a code sample:

import SwiftUI import ArcGIS struct LayerView: View { var map: Map var body: some View { List { ForEach(map.operationalLayers, id:\.self) { layer in SublayerView(layer: layer) } } .onAppear { //make all group layers visible by default map.operationalLayers.forEach { layer in if (layer.subLayerContents.count > 0) { layer.isVisible = true layer.subLayerContents.forEach { sublayer in if (sublayer.subLayerContents.count > 0) { sublayer.isVisible = true } } } } } } } struct SublayerView: View { var layer: Layer @State private var expanded: Bool = false var body: some View { if (layer.subLayerContents.count > 0) { DisclosureGroup(layer.name, isExpanded: $expanded) { ForEach(layer.subLayerContents.reversed(), id:\.self.name) { sublayer in if (sublayer.subLayerContents.count > 0) { SublayerView(layer: sublayer as! Layer) } else { Toggle(isOn: Binding<Bool>(get: {sublayer.isVisible}, set: {sublayer.isVisible = $0 })) { Text(sublayer.name) } } } } } else { Toggle(isOn: Binding<Bool>(get: {layer.isVisible}, set: {layer.isVisible = $0})) { Text(layer.name) } } } }

Re: Swift Layer List Examples

MarkDostal — Fri, 07 Apr 2023 14:49:21 GMT

Hello! Thank you for your question and I'm glad you found a solution. A legend or "layers list" is something that we will be implementing in the Swift Toolkit at some point, but there's no firm release date yet.

In the meantime, you solution looks good! You can also take a look at the v100.15 Toolkit's LegendViewController, and the actual code.

There are a few things in that code that may be of interest, depending on your requirements:

- Including base maps in the layers list

- Ensuring the Map and Layers are loaded prior to displaying the list

- Displaying symbol swatches for layers

- Hiding/showing scale-dependent layers depending on map scale (applicable primarily for Legends).

Nice work! If you have any more questions, please reach out!

Mark

Re: Swift Layer List Examples

Justin_Greco — Mon, 17 Apr 2023 13:18:56 GMT

Thank you Mark. I was able to incorporate a legend and a opacity slider. Here is some code in case anyone else is trying to do the same.

import SwiftUI import ArcGIS class LegendSwatch: ObservableObject, Identifiable , Hashable { static func == (lhs: LegendSwatch, rhs: LegendSwatch) -> Bool { return lhs.label == rhs.label && lhs.swatch == rhs.swatch } @Published var label: String @Published var swatch: UIImage init(label: String, swatch: UIImage) { self.label = label self.swatch = swatch } func hash(into hasher: inout Hasher) { hasher.combine(label) hasher.combine(swatch) } } struct LayerInfoView: View { @State var layer: Layer @State private var swatches: [LegendSwatch] = [] var body: some View { ScrollView { VStack { Text("Opacity") Slider(value: $layer.opacity, in: 0...1, step: 0.1) { } minimumValueLabel: { Text("0%") } maximumValueLabel: { Text("100%") } ForEach(swatches, id: \.self) { swatch in HStack { Image(uiImage: swatch.swatch) Text(swatch.label) } } } } .task { let infos: [LegendInfo] = try! await layer.legendInfos infos.forEach { info in Task { let swatch = try? await info.symbol?.makeSwatch(scale: 1.0) self.swatches.append(LegendSwatch(label: info.name, swatch: swatch!)) } } } } }