Trace utility network

View inAndroidFormsUWPWPFWinUIiOSView on GitHub

Discover connected features in a utility network using connected, subnetwork, upstream, and downstream traces.

Image of trace utility network

Use case

You can use a trace to visualize and validate the network topology of a utility network for quality assurance. Subnetwork traces are used for validating whether subnetworks, such as circuits or zones, are defined or edited appropriately.

How to use the sample

Tap on one or more features while 'Add starting locations' or 'Add barriers' is selected. When a junction feature is identified, you may be prompted to select a terminal. When an edge feature is identified, the distance from the tapped location to the beginning of the edge feature will be computed. Select the type of trace using the drop down menu. Tap 'Trace' to initiate a trace on the network. Tap 'Reset' to clear the trace parameters and start over.

How it works

  1. Create a MapView and subscribe to its GeoViewTapped event.
  2. Create and load a ServiceGeodatabase with a feature service URL and get tables by their layer IDs.
  3. Create a Map that contains FeatureLayer(s) created from the ServiceGeodatabase's tables.
  4. Create and load a UtilityNetwork with the same feature service URL and this Map.
  5. Add a GraphicsOverlay with symbology that distinguishes starting locations from barriers.
  6. Identify features on the map and add a Graphic that represents its purpose (starting location or barrier) at the tapped location.
  7. Create a UtilityElement for the identified feature.
  8. Determine the type of this element using its UtilityNetworkSource.SourceType property.
  9. If the element is a junction with more than one terminal, display a terminal picker. Then set the junction's UtilityTerminal property with the selected terminal.
  10. If an edge, set its FractionAlongEdge property using GeometryEngine.FractionAlong.
  11. Add this UtilityElement to a collection of starting locations or barriers.
  12. Create UtilityTraceParameters with the selected trace type along with the collected starting locations and barriers (if applicable).
  13. Set the UtilityTraceParameters.TraceConfiguration with the tier's UtilityTier.GetDefaultTraceConfiguration() result.
  14. Run a UtilityNetwork.TraceAsync with the specified parameters.
  15. For every FeatureLayer in the map, select the features returned with GetFeaturesForElementsAsync from the elements matching their UtilityNetworkSource.FeatureTable with the layer's FeatureTable.

Relevant API

  • FractionAlong
  • UtilityAssetType
  • UtilityDomainNetwork
  • UtilityElement
  • UtilityElementTraceResult
  • UtilityNetwork
  • UtilityNetworkDefinition
  • UtilityNetworkSource
  • UtilityTerminal
  • UtilityTier
  • UtilityTraceConfiguration
  • UtilityTraceParameters
  • UtilityTraceResult
  • UtilityTraceType
  • UtilityTraversability

About the data

The Naperville electrical network feature service, hosted on ArcGIS Online, contains a utility network used to run the subnetwork-based trace shown in this sample.

Additional information

Using utility network on ArcGIS Enterprise 10.8 requires an ArcGIS Enterprise member account licensed with the Utility Network user type extension. Please refer to the utility network services documentation.

Tags

condition barriers, downstream trace, network analysis, subnetwork trace, trace configuration, traversability, upstream trace, utility network, validate consistency

Sample Code

TraceUtilityNetwork.cs
Use dark colors for code blocksCopy
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
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
// Copyright 2019 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: http://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.

using ArcGISRuntime;
using Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Http;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Security;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI;
using Esri.ArcGISRuntime.UI.Controls;
using Esri.ArcGISRuntime.UtilityNetworks;
using Foundation;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;
using UIKit;

namespace ArcGISRuntimeXamarin.Samples.TraceUtilityNetwork
{
    [Register("TraceUtilityNetwork")]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Trace utility network",
        category: "Utility network",
        description: "Discover connected features in a utility network using connected, subnetwork, upstream, and downstream traces.",
        instructions: "Tap on one or more features while 'Add starting locations' or 'Add barriers' is selected. When a junction feature is identified, you may be prompted to select a terminal. When an edge feature is identified, the distance from the tapped location to the beginning of the edge feature will be computed. Select the type of trace using the drop down menu. Tap 'Trace' to initiate a trace on the network. Tap 'Reset' to clear the trace parameters and start over.",
        tags: new[] { "condition barriers", "downstream trace", "network analysis", "subnetwork trace", "trace configuration", "traversability", "upstream trace", "utility network", "validate consistency" })]
    public class TraceUtilityNetwork : UIViewController
    {
        // Hold references to UI controls.
        private MapView _myMapView;
        private UIToolbar _toolbar;
        private UIBarButtonItem _resetButton;
        private UIBarButtonItem _traceButton;
        private UISegmentedControl _startBarrierPicker;
        private UILabel _statusLabel;
        private UIActivityIndicatorView _activityIndicator;
        private UIButton _tracePickerButton;

        // Feature service for an electric utility network in Naperville, Illinois.
        private const string FeatureServiceUrl = "https://sampleserver7.arcgisonline.com/server/rest/services/UtilityNetwork/NapervilleElectric/FeatureServer";

        // Viewpoint in the utility network area.
        private Viewpoint _startingViewpoint = new Viewpoint(new Envelope(-9812980.8041217551, 5128523.87694709, -9812798.4363710005, 5128627.6261982173, SpatialReferences.WebMercator));

        // Utility network objects.
        private UtilityNetwork _utilityNetwork;
        private List<UtilityElement> _startingLocations = new List<UtilityElement>();
        private List<UtilityElement> _barriers = new List<UtilityElement>();
        private UtilityTier _mediumVoltageTier;
        private UtilityTraceType _utilityTraceType;

        // Task completion source for the user selected terminal.
        private TaskCompletionSource<string> _terminalCompletionSource = null;

        // Markers for the utility elements.
        private SimpleMarkerSymbol _startingPointSymbol;
        private SimpleMarkerSymbol _barrierPointSymbol;

        public TraceUtilityNetwork()
        {
            Title = "Trace a utility network";
        }

        private async void Initialize()
        {
            // As of ArcGIS Enterprise 10.8.1, using utility network functionality requires a licensed user. The following login for the sample server is licensed to perform utility network operations.
            AuthenticationManager.Current.ChallengeHandler = new ChallengeHandler(async (info) =>
            {
                try
                {
                    // WARNING: Never hardcode login information in a production application. This is done solely for the sake of the sample.
                    string sampleServer7User = "viewer01";
                    string sampleServer7Pass = "I68VGU^nMurF";

                    return await AuthenticationManager.Current.GenerateCredentialAsync(info.ServiceUri, sampleServer7User, sampleServer7Pass);
                }
                catch (Exception ex)
                {
                    Debug.WriteLine(ex.Message);
                    return null;
                }
            });

            try
            {
                _activityIndicator.StartAnimating();
                _statusLabel.Text = "Loading Utility Network...";

                // Create a map.
                _myMapView.Map = new Map(BasemapStyle.ArcGISStreetsNight)
                {
                    InitialViewpoint = _startingViewpoint
                };

                // Add the layer with electric distribution lines.
                FeatureLayer lineLayer = new FeatureLayer(new Uri($"{FeatureServiceUrl}/3"));
                UniqueValue mediumVoltageValue = new UniqueValue("N/A", "Medium Voltage", new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, System.Drawing.Color.DarkCyan, 3), 5);
                UniqueValue lowVoltageValue = new UniqueValue("N/A", "Low Voltage", new SimpleLineSymbol(SimpleLineSymbolStyle.Dash, System.Drawing.Color.DarkCyan, 3), 3);
                lineLayer.Renderer = new UniqueValueRenderer(new List<string>() { "ASSETGROUP" }, new List<UniqueValue>() { mediumVoltageValue, lowVoltageValue }, "", new SimpleLineSymbol());
                _myMapView.Map.OperationalLayers.Add(lineLayer);

                // Add the layer with electric devices.
                FeatureLayer electricDevicelayer = new FeatureLayer(new Uri($"{FeatureServiceUrl}/0"));
                _myMapView.Map.OperationalLayers.Add(electricDevicelayer);

                // Set the selection color for features in the map view.
                _myMapView.SelectionProperties = new SelectionProperties(System.Drawing.Color.Yellow);

                // Create and load the utility network.
                _utilityNetwork = await UtilityNetwork.CreateAsync(new Uri(FeatureServiceUrl), _myMapView.Map);

                // Get the utility tier used for traces in this network. For this data set, the "Medium Voltage Radial" tier from the "ElectricDistribution" domain network is used.
                UtilityDomainNetwork domainNetwork = _utilityNetwork.Definition.GetDomainNetwork("ElectricDistribution");
                _mediumVoltageTier = domainNetwork.GetTier("Medium Voltage Radial");

                // More complex datasets may require using utility trace configurations from different tiers. The following LINQ expression gets all tiers present in the utility network.
                //IEnumerable<UtilityTier> tiers = _utilityNetwork.Definition.DomainNetworks.Select(domain => domain.Tiers).SelectMany(tier => tier);

                // Create symbols for starting locations and barriers.
                _startingPointSymbol = new SimpleMarkerSymbol(SimpleMarkerSymbolStyle.Cross, System.Drawing.Color.LightGreen, 25d);
                _barrierPointSymbol = new SimpleMarkerSymbol(SimpleMarkerSymbolStyle.X, System.Drawing.Color.OrangeRed, 25d);

                // Create a graphics overlay.
                GraphicsOverlay graphicsOverlay = new GraphicsOverlay();
                _myMapView.GraphicsOverlays.Add(graphicsOverlay);

                // Set the instruction text.
                _statusLabel.Text = "Click on the network lines or points to add a utility element.";
            }
            catch (Exception ex)
            {
                _statusLabel.Text = "Loading Utility Network failed...";
                new UIAlertView("Error", ex.Message, (IUIAlertViewDelegate)null, "OK", null).Show();
            }
            finally
            {
                _activityIndicator.StopAnimating();
            }
        }

        private async void OnGeoViewTapped(object sender, GeoViewInputEventArgs e)
        {
            try
            {
                _activityIndicator.StartAnimating();
                _statusLabel.Text = "Identifying trace locations...";

                // Identify the feature to be used.
                IEnumerable<IdentifyLayerResult> identifyResult = await _myMapView.IdentifyLayersAsync(e.Position, 10.0, false);
                ArcGISFeature feature = identifyResult?.FirstOrDefault()?.GeoElements?.FirstOrDefault() as ArcGISFeature;
                if (feature == null) { return; }

                // Create element from the identified feature.
                UtilityElement element = _utilityNetwork.CreateElement(feature);

                if (element.NetworkSource.SourceType == UtilityNetworkSourceType.Junction)
                {
                    // Select terminal for junction feature.
                    IEnumerable<UtilityTerminal> terminals = element.AssetType.TerminalConfiguration?.Terminals;
                    if (terminals?.Count() > 1)
                    {
                        element.Terminal = await WaitForTerminal(terminals);
                    }
                    _statusLabel.Text = $"Terminal: {element.Terminal?.Name ?? "default"}";
                }
                else if (element.NetworkSource.SourceType == UtilityNetworkSourceType.Edge)
                {
                    // Compute how far tapped location is along the edge feature.
                    if (feature.Geometry is Polyline line)
                    {
                        line = GeometryEngine.RemoveZ(line) as Polyline;
                        element.FractionAlongEdge = GeometryEngine.FractionAlong(line, e.Location, -1);
                        _statusLabel.Text = $"Fraction along edge: {element.FractionAlongEdge}";
                    }
                }

                // Check whether starting location or barrier is added to update the right collection and symbology.
                Symbol symbol = null;
                if (_startBarrierPicker.SelectedSegment == 0)
                {
                    _startingLocations.Add(element);
                    symbol = _startingPointSymbol;
                }
                else
                {
                    _barriers.Add(element);
                    symbol = _barrierPointSymbol;
                }

                // Add a graphic for the new utility element.
                Graphic traceLocationGraphic = new Graphic(feature.Geometry as MapPoint ?? e.Location, symbol);
                _myMapView.GraphicsOverlays.FirstOrDefault()?.Graphics.Add(traceLocationGraphic);
            }
            catch (Exception ex)
            {
                _statusLabel.Text = "Identifying locations failed...";
                new UIAlertView("Error", ex.Message, (IUIAlertViewDelegate)null, "OK", null).Show();
            }
            finally
            {
                if (_statusLabel.Text.Equals("Identifying trace locations...")) { _statusLabel.Text = "Could not identify location."; }
                _activityIndicator.StopAnimating();
            }
        }

        private async Task<UtilityTerminal> WaitForTerminal(IEnumerable<UtilityTerminal> terminals)
        {
            try
            {
                // Prevent user from tapping map while selecting terminal.
                _myMapView.GeoViewTapped -= OnGeoViewTapped;

                // Start the UI for the user choosing the junction.
                UIAlertController prompt = UIAlertController.Create(null, "Choose terminal", UIAlertControllerStyle.ActionSheet);

                foreach (UtilityTerminal terminal in terminals)
                {
                    prompt.AddAction(UIAlertAction.Create(terminal.Name, UIAlertActionStyle.Default, Choose_Click));
                }

                // Needed to prevent crash on iPad.
                UIPopoverPresentationController ppc = prompt.PopoverPresentationController;
                if (ppc != null)
                {
                    ppc.SourceView = _toolbar;
                    ppc.PermittedArrowDirections = UIPopoverArrowDirection.Down;
                    ppc.DidDismiss += (s, e) => _terminalCompletionSource.TrySetCanceled();
                }

                PresentViewController(prompt, true, null);

                // Wait for the user to select a terminal.
                _terminalCompletionSource = new TaskCompletionSource<string>();
                string selectedName = await _terminalCompletionSource.Task;
                return terminals.Where(x => x.Name.Equals(selectedName)).FirstOrDefault();
            }
            finally
            {
                // Enable the main UI again.
                _myMapView.GeoViewTapped += OnGeoViewTapped;
            }
        }

        private void Choose_Click(UIAlertAction action)
        {
            _terminalCompletionSource.TrySetResult(action.Title);
        }

        private void ChangeTraceType(object sender, EventArgs e)
        {
            // Prevent user from tapping map while selecting a trace type.
            _myMapView.GeoViewTapped -= OnGeoViewTapped;

            // Start the UI for the user choosing the trace type.
            UIAlertController prompt = UIAlertController.Create(null, "Choose trace type", UIAlertControllerStyle.ActionSheet);

            // Add a selection action for every valid trace type.
            foreach (string name in new string[] { "Connected", "Subnetwork", "Upstream", "Downstream" })
            {
                prompt.AddAction(UIAlertAction.Create(name, UIAlertActionStyle.Default, TraceTypeClick));
            }

            // Needed to prevent crash on iPad.
            UIPopoverPresentationController ppc = prompt.PopoverPresentationController;
            if (ppc != null)
            {
                ppc.SourceView = _tracePickerButton;
                ppc.PermittedArrowDirections = UIPopoverArrowDirection.Down;
            }

            PresentViewController(prompt, true, null);

            // Enable the main UI again.
            _myMapView.GeoViewTapped += OnGeoViewTapped;
        }

        private void TraceTypeClick(UIAlertAction action)
        {
            _utilityTraceType = (UtilityTraceType)Enum.Parse(typeof(UtilityTraceType), action.Title);
            _tracePickerButton.SetTitle($"Trace type: {_utilityTraceType}", UIControlState.Normal);
        }

        private async void OnTrace(object sender, EventArgs e)
        {
            try
            {
                // Update the UI.
                _activityIndicator.StartAnimating();
                _statusLabel.Text = $"Running {_utilityTraceType.ToString().ToLower()} trace...";

                // Clear previous selection from the layers.
                _myMapView.Map.OperationalLayers.OfType<FeatureLayer>().ToList().ForEach(layer => layer.ClearSelection());

                // Build trace parameters.
                UtilityTraceParameters parameters = new UtilityTraceParameters(_utilityTraceType, _startingLocations);
                foreach (UtilityElement barrier in _barriers)
                {
                    parameters.Barriers.Add(barrier);
                }

                // Set the trace configuration using the tier from the utility domain network.
                parameters.TraceConfiguration = _mediumVoltageTier.GetDefaultTraceConfiguration();

                //  Get the trace result from the utility network.
                IEnumerable<UtilityTraceResult> traceResult = await _utilityNetwork.TraceAsync(parameters);
                UtilityElementTraceResult elementTraceResult = traceResult?.FirstOrDefault() as UtilityElementTraceResult;

                // Check if there are any elements in the result.
                if (elementTraceResult?.Elements?.Count > 0)
                {
                    foreach (FeatureLayer layer in _myMapView.Map.OperationalLayers.OfType<FeatureLayer>())
                    {
                        IEnumerable<UtilityElement> elements = elementTraceResult.Elements.Where(element => element.NetworkSource.Name == layer.FeatureTable.TableName);
                        IEnumerable<Feature> features = await _utilityNetwork.GetFeaturesForElementsAsync(elements);
                        layer.SelectFeatures(features);
                    }
                }
                _statusLabel.Text = "Trace completed.";
            }
            catch (Exception ex)
            {
                _statusLabel.Text = "Trace failed...";
                if (ex is ArcGISWebException && ex.Message == null)
                {
                    new UIAlertView(ex.GetType().Name, "Trace failed.", (IUIAlertViewDelegate)null, "OK", null).Show();
                }
                else
                {
                    new UIAlertView(ex.GetType().Name, ex.Message, (IUIAlertViewDelegate)null, "OK", null).Show();
                }
            }
            finally
            {
                _activityIndicator.StopAnimating();
            }
        }

        private void OnReset(object sender, EventArgs e)
        {
            // Reset the UI.
            _statusLabel.Text = "Click on the network lines or points to add a utility element.";
            _activityIndicator.StopAnimating();

            // Clear collections of starting locations and barriers.
            _startingLocations.Clear();
            _barriers.Clear();

            // Clear the map of any locations, barriers and trace result.
            _myMapView.GraphicsOverlays.FirstOrDefault()?.Graphics.Clear();
            _myMapView.Map.OperationalLayers.OfType<FeatureLayer>().ToList().ForEach(layer => layer.ClearSelection());
        }

        public override void LoadView()
        {
            // Create the views.
            View = new UIView() { BackgroundColor = ApplicationTheme.BackgroundColor };

            _myMapView = new MapView();
            _myMapView.TranslatesAutoresizingMaskIntoConstraints = false;

            _statusLabel = new UILabel
            {
                Text = "Instructions",
                AdjustsFontSizeToFitWidth = true,
                TextAlignment = UITextAlignment.Center,
                BackgroundColor = UIColor.FromWhiteAlpha(0, .6f),
                TextColor = UIColor.White,
                Lines = 1,
                TranslatesAutoresizingMaskIntoConstraints = false
            };

            _tracePickerButton = new UIButton(UIButtonType.System);
            _tracePickerButton.SetTitle("Trace type: Connected", UIControlState.Normal);
            _tracePickerButton.TranslatesAutoresizingMaskIntoConstraints = false;

            _startBarrierPicker = new UISegmentedControl(new string[] { "Start", "Barrier" });
            _startBarrierPicker.SelectedSegment = 0;

            _traceButton = new UIBarButtonItem();
            _traceButton.Title = "Trace";

            _resetButton = new UIBarButtonItem();
            _resetButton.Title = "Reset";

            _toolbar = new UIToolbar();
            _toolbar.TranslatesAutoresizingMaskIntoConstraints = false;
            _toolbar.Items = new[]
            {
                new UIBarButtonItem(_startBarrierPicker),
                new UIBarButtonItem(UIBarButtonSystemItem.FlexibleSpace),
                _traceButton,
                _resetButton
            };

            _activityIndicator = new UIActivityIndicatorView(UIActivityIndicatorViewStyle.WhiteLarge)
            {
                TranslatesAutoresizingMaskIntoConstraints = false,
                HidesWhenStopped = true,
                BackgroundColor = UIColor.FromWhiteAlpha(0, .5f)
            };

            // Add the views.
            View.AddSubviews(_myMapView, _statusLabel, _tracePickerButton, _toolbar, _activityIndicator);

            // Lay out the views.
            NSLayoutConstraint.ActivateConstraints(new[]
                {
                    _myMapView.TopAnchor.ConstraintEqualTo(View.SafeAreaLayoutGuide.TopAnchor),
                    _myMapView.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
                    _myMapView.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
                    _myMapView.BottomAnchor.ConstraintEqualTo(_tracePickerButton.TopAnchor),

                    _tracePickerButton.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
                    _tracePickerButton.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
                    _tracePickerButton.BottomAnchor.ConstraintEqualTo(_toolbar.TopAnchor),
                    _tracePickerButton.HeightAnchor.ConstraintEqualTo(40),

                    _toolbar.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
                    _toolbar.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
                    _toolbar.BottomAnchor.ConstraintEqualTo(View.SafeAreaLayoutGuide.BottomAnchor),

                    _statusLabel.TopAnchor.ConstraintEqualTo(_myMapView.TopAnchor),
                    _statusLabel.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
                    _statusLabel.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
                    _statusLabel.HeightAnchor.ConstraintEqualTo(40),

                    _activityIndicator.TopAnchor.ConstraintEqualTo(_statusLabel.BottomAnchor),
                    _activityIndicator.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
                    _activityIndicator.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
                    _activityIndicator.BottomAnchor.ConstraintEqualTo(View.BottomAnchor)
                }
            );
        }

        public override void ViewWillAppear(bool animated)
        {
            base.ViewWillAppear(animated);

            // Subscribe to events.
            _myMapView.GeoViewTapped += OnGeoViewTapped;
            _traceButton.Clicked += OnTrace;
            _resetButton.Clicked += OnReset;
            _tracePickerButton.TouchUpInside += ChangeTraceType;
        }

        public override void ViewDidDisappear(bool animated)
        {
            base.ViewDidDisappear(animated);

            // Unsubscribe from events, per best practice.
            _myMapView.GeoViewTapped -= OnGeoViewTapped;
            _traceButton.Clicked -= OnTrace;
            _resetButton.Clicked -= OnReset;
            _tracePickerButton.TouchUpInside -= ChangeTraceType;
        }

        public override void ViewDidLoad()
        {
            base.ViewDidLoad();
            Initialize();
        }
    }
}

Your browser is no longer supported. Please upgrade your browser for the best experience. See our browser deprecation post for more details.