Click or drag to resize

PolylineBarrier Class

A polyline barrier is used to restrict route solving.
Inheritance Hierarchy
SystemObject
  Esri.ArcGISRuntime.Tasks.NetworkAnalysisPolylineBarrier

Namespace:  Esri.ArcGISRuntime.Tasks.NetworkAnalysis
Assembly:  Esri.ArcGISRuntime (in Esri.ArcGISRuntime.dll) Version: 100.7.0.0
Syntax
C#
public sealed class PolylineBarrier

The PolylineBarrier type exposes the following members.

Constructors
  NameDescription
Public methodCode examplePolylineBarrier
Initializes a new instance of the PolylineBarrier class.
Top
Properties
  NameDescription
Public propertyBarrierId
Gets or sets the polyline barrier ID.
Public propertyGeometry
Gets the polyline barrier's geometry.
Public propertyName
Gets or sets the name of the barrier.
Public propertyType
Gets or sets the polyline barrier's type.
Top
Methods
  NameDescription
Public methodGetScaleFactorForCost
Gets scale factor for cost.
Public methodSetScaleFactorForCost
Sets scale factor for cost.
Top
Remarks
A class that represents a linear feature to be avoided (or penalized) by a route. Polyline_barrier may represent a linear feature (e.g., a subpath in the network) to be avoided (i.e., not crossed or followed) by a route or to penalize/delay a route along any portions of the feature traversed by the route (e.g., a stretch of interstate with temporarily reduced speed limits due to local construction along an adjacent lane).
Examples

Android

Example Name: FindServiceArea

Find the service area within a network from a given point.

Code example screen shot.

C#
// Copyright 2018 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 Android.App;
using Android.OS;
using Android.Views;
using Android.Widget;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.Tasks.NetworkAnalysis;
using Esri.ArcGISRuntime.UI;
using Esri.ArcGISRuntime.UI.Controls;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace ArcGISRuntime.Samples.FindServiceArea
{
    [Activity (ConfigurationChanges=Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        "Find service area (interactive)",
        "Network Analysis",
        "Demonstrates how to find services areas around a point using the ServiceAreaTask. A service area shows locations that can be reached from a facility based off a certain impedance [travel time in this case]. Service areas for a two and five minute travel time are used. Barriers can also be added which can effect the service area by not letting traffic through and adding to the time to get to locations.",
        "-To add a facility, click the facility button, then click anywhere on the MapView.\n-To add a barrier, click the barrier button, and click multiple locations on MapView.\n-Double tap on the MapView to finish drawing the barrier.\n-To show service areas around facilities that were added, click the show service areas button.\n-Click the reset button to clear all graphics and features.",
        "ArcGISMap, GraphicsOverlay, MapView, PolylineBarrier, ServiceAreaFacility, ServiceAreaParameters, ServiceAreaPolygon, ServiceAreaResult, ServiceAreaTask, SketchEditor")]
    public class FindServiceArea : Activity
    {
        // Hold a reference to the map view.
        private MapView _myMapView;

        // Uri for the service area around San Diego.
        private Uri _serviceAreaUri = new Uri("https://sampleserver6.arcgisonline.com/arcgis/rest/services/NetworkAnalysis/SanDiego/NAServer/ServiceArea");

        // Create buttons for the UI.
        private Button _facilityButton;
        private Button _barrierButton;
        private Button _serviceAreasButton;
        private Button _resetButton;

        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            Title = "Find service area (interactive)";

            CreateLayout();
            Initialize();
        }

        private void CreateLayout()
        {
            // Create a new layout for the entire page.
            LinearLayout layout = new LinearLayout(this) { Orientation = Orientation.Vertical };

            // Add layouts for the buttons.
            LinearLayout topRow = new LinearLayout(this) { Orientation = Orientation.Horizontal };
            LinearLayout bottomRow = new LinearLayout(this) { Orientation = Orientation.Horizontal };

            // Make a layout parameter for the buttons.
            LinearLayout.LayoutParams param = new LinearLayout.LayoutParams(
                ViewGroup.LayoutParams.MatchParent,
                ViewGroup.LayoutParams.MatchParent,
                1.0f
            );

            // Create a button to reset the route display, add it to the toolbar.
            _facilityButton = new Button(this) { Text = "Place Facility", LayoutParameters = param };
            _facilityButton.Click += PlaceFacilityButtonClick;
            topRow.AddView(_facilityButton);

            // Create a button to reset the route display, add it to the toolbar.
            _barrierButton = new Button(this) { Text = "Draw Barrier", LayoutParameters = param };
            //_barrierButton.SetWidth(toolbar.Width);
            _barrierButton.Click += DrawBarrierButtonClick;
            topRow.AddView(_barrierButton);

            // Create a button to reset the route display, add it to the toolbar.
            _serviceAreasButton = new Button(this) { Text = "Show Service Areas", LayoutParameters = param };
            _serviceAreasButton.Click += ShowServiceAreasButtonClick;
            bottomRow.AddView(_serviceAreasButton);

            // Create a button to reset the route display, add it to the toolbar.
            _resetButton = new Button(this) { Text = "Reset", LayoutParameters = param };
            _resetButton.Click += ResetClick;
            bottomRow.AddView(_resetButton);

            // Add rows of buttons to the layout.
            layout.AddView(topRow);
            layout.AddView(bottomRow);

            // Add the map view to the layout.
            _myMapView = new MapView(this);
            layout.AddView(_myMapView);

            // Show the layout in the app.
            SetContentView(layout);
        }

        private void Initialize()
        {
            // Center the map on San Diego.
            Map streetsMap = new Map(Basemap.CreateLightGrayCanvasVector())
            {
                InitialViewpoint = new Viewpoint(32.73, -117.14, 30000)
            };
            _myMapView.Map = streetsMap;

            // Create graphics overlays for all of the elements of the map.
            _myMapView.GraphicsOverlays.Add(new GraphicsOverlay());

            // Add a new behavior for double taps on the MapView.
            _myMapView.GeoViewDoubleTapped += (s, e) =>
            {
                // If the sketch editor complete command is enabled, a sketch is in progress.
                if (_myMapView.SketchEditor.CompleteCommand.CanExecute(null))
                {
                    // Set the event as handled.
                    e.Handled = true;

                    // Finish any drawing.
                    _myMapView.SketchEditor.CompleteCommand.Execute(null);

                    // Update UI.
                    _barrierButton.Text = "Draw barrier";
                }
            };
        }

        private async void PlaceFacilityButtonClick(object sender, EventArgs e)
        {
            // Disable the button so the user recognizes that they are placing a facility.
            _facilityButton.Enabled = false;

            try
            {
                // Let the user tap on the map view using the point sketch mode.
                SketchCreationMode creationMode = SketchCreationMode.Point;
                Geometry geometry = await _myMapView.SketchEditor.StartAsync(creationMode, false);

                // Symbology for a facility.
                PictureMarkerSymbol facilitySymbol = new PictureMarkerSymbol(new Uri("https://static.arcgis.com/images/Symbols/SafetyHealth/Hospital.png"))
                {
                    Height = 30,
                    Width = 30
                };

                // Create a graphic for the facility.
                Graphic facilityGraphic = new Graphic(geometry, new Dictionary<string, object>() { { "Type", "Facility" } }, facilitySymbol)
                {
                    ZIndex = 2
                };

                // Add the graphic to the graphics overlay.
                _myMapView.GraphicsOverlays[0].Graphics.Add(facilityGraphic);
            }
            catch (TaskCanceledException)
            {
                // Ignore this exception.
            }
            catch (Exception ex)
            {
                // Report exceptions.
                CreateErrorDialog("Error drawing facility:\n" + ex.Message);
            }

            // Enable the button when the user is done.
            _facilityButton.Enabled = true;
        }

        private async void DrawBarrierButtonClick(object sender, EventArgs e)
        {
            // Finish any drawings in progress.
            if (_barrierButton.Text != "Draw barrier")
            {
                // Finish the sketch.
                if (_myMapView.SketchEditor.CompleteCommand.CanExecute(null))
                {
                    _myMapView.SketchEditor.CompleteCommand.Execute(null);
                }

                // Update the UI.
                _barrierButton.Text = "Draw barrier";

                return;
            }

            try
            {
                // Update the UI.
                _barrierButton.Text = "Finish drawing";

                // Let the user draw on the map view using the polyline sketch mode.
                SketchCreationMode creationMode = SketchCreationMode.Polyline;
                Geometry geometry = await _myMapView.SketchEditor.StartAsync(creationMode, false);

                // Symbol for the barriers.
                SimpleLineSymbol barrierSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, System.Drawing.Color.Black, 5.0f);

                // Create the graphic to be used for barriers.
                Graphic barrierGraphic = new Graphic(geometry, new Dictionary<string, object>() { { "Type", "Barrier" } }, barrierSymbol)
                {
                    ZIndex = 1
                };

                // Add a graphic from the polyline the user drew.
                _myMapView.GraphicsOverlays[0].Graphics.Add(barrierGraphic);
            }
            catch (TaskCanceledException)
            {
                // Ignore this exception.
            }
            catch (Exception ex)
            {
                // Report exceptions.
                CreateErrorDialog("Error drawing barrier:\n" + ex.Message);
            }

            // Enable the button when the user is done.
            _barrierButton.Enabled = true;
        }

        private async void ShowServiceAreasButtonClick(object sender, EventArgs e)
        {
            // Finish any drawings in progress.
            if (_myMapView.SketchEditor.CompleteCommand.CanExecute(null))
            {
                _myMapView.SketchEditor.CompleteCommand.Execute(null);
            }

            // Update the UI.
            _barrierButton.Text = "Draw barrier";

            // Use a local variable for the graphics overlay.
            GraphicCollection allGraphics = _myMapView.GraphicsOverlays[0].Graphics;

            // Get a list of the facilities from the graphics overlay.
            List<ServiceAreaFacility> serviceAreaFacilities = (from g in allGraphics
                                                               where (string)g.Attributes["Type"] == "Facility"
                                                               select new ServiceAreaFacility((MapPoint)g.Geometry)).ToList();

            // Check that there is at least 1 facility to find a service area for.
            if (!serviceAreaFacilities.Any())
            {
                CreateErrorDialog("Must have at least one Facility!");
                return;
            }

            // Create the service area task and parameters based on the Uri.
            ServiceAreaTask serviceAreaTask = await ServiceAreaTask.CreateAsync(_serviceAreaUri);

            // Store the default parameters for the service area in an object.
            ServiceAreaParameters serviceAreaParameters = await serviceAreaTask.CreateDefaultParametersAsync();

            // Add impedance cutoffs for facilities (drive time minutes).
            serviceAreaParameters.DefaultImpedanceCutoffs.Add(2.0);
            serviceAreaParameters.DefaultImpedanceCutoffs.Add(5.0);

            // Set the level of detail for the polygons.
            serviceAreaParameters.PolygonDetail = ServiceAreaPolygonDetail.High;

            // Get a list of the barriers from the graphics overlay.
            List<PolylineBarrier> polylineBarriers = (from g in allGraphics
                                                      where (string)g.Attributes["Type"] == "Barrier"
                                                      select new PolylineBarrier((Polyline)g.Geometry)).ToList();

            // Add the barriers to the service area parameters.
            serviceAreaParameters.SetPolylineBarriers(polylineBarriers);

            // Update the parameters to include all of the placed facilities.
            serviceAreaParameters.SetFacilities(serviceAreaFacilities);

            // Clear existing graphics for service areas.
            foreach (Graphic g in allGraphics.ToList())
            {
                // Check if the graphic g is a service area.
                if ((string)g.Attributes["Type"] == "ServiceArea")
                {
                    allGraphics.Remove(g);
                }
            }

            try
            {
                // Solve for the service area of the facilities.
                ServiceAreaResult result = await serviceAreaTask.SolveServiceAreaAsync(serviceAreaParameters);

                // Loop over each facility.
                for (int i = 0; i < serviceAreaFacilities.Count; i++)
                {
                    // Create list of polygons from a service facility.
                    List<ServiceAreaPolygon> polygons = result.GetResultPolygons(i).ToList();

                    // Symbol for the outline of the service areas.
                    SimpleLineSymbol serviceOutline = new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, System.Drawing.Color.DarkGray, 3.0f);

                    // Create a list of fill symbols for the polygons.
                    List<SimpleFillSymbol> fillSymbols = new List<SimpleFillSymbol>();
                    fillSymbols.Add(new SimpleFillSymbol(SimpleFillSymbolStyle.Solid, System.Drawing.Color.FromArgb(70, 255, 0, 0), serviceOutline));
                    fillSymbols.Add(new SimpleFillSymbol(SimpleFillSymbolStyle.Solid, System.Drawing.Color.FromArgb(70, 255, 165, 0), serviceOutline));

                    // Loop over every polygon in every facilities result.
                    for (int j = 0; j < polygons.Count; j++)
                    {
                        // Create the graphic for the service areas, alternating between fill symbols.
                        Graphic serviceGraphic = new Graphic(polygons[j].Geometry, new Dictionary<string, object>() { { "Type", "ServiceArea" } }, fillSymbols[j % 2])
                        {
                            ZIndex = 0
                        };

                        // Add graphic for service area. Alternate the color of each polygon.
                        allGraphics.Add(serviceGraphic);
                    }
                }
            }
            catch (Esri.ArcGISRuntime.Http.ArcGISWebException exception)
            {
                if (exception.Message.ToString().Equals("Unable to complete operation."))
                {
                    CreateErrorDialog("Facility not within San Diego area!");
                }
                else
                {
                    CreateErrorDialog("An ArcGIS web exception occurred. \n" + exception.Message);
                }
            }
        }

        private void ResetClick(object sender, EventArgs e)
        {
            // Clear all of the graphics.
            _myMapView.GraphicsOverlays[0].Graphics.Clear();
        }

        private void CreateErrorDialog(string message)
        {
            // Create a dialog to show message to user.
            AlertDialog alert = new AlertDialog.Builder(this).Create();
            alert.SetMessage(message);
            alert.Show();
        }
    }
}
Examples

Xamarin Forms Android

Example Name: FindServiceArea

Find the service area within a network from a given point.

Code example screen shot.

C#
// Copyright 2018 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 Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.Tasks.NetworkAnalysis;
using Esri.ArcGISRuntime.UI;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Xamarin.Forms;

namespace ArcGISRuntime.Samples.FindServiceArea
{
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        "Find service area (interactive)",
        "Network Analysis",
        "Demonstrates how to find services areas around a point using the ServiceAreaTask. A service area shows locations that can be reached from a facility based off a certain impedance [travel time in this case]. Service areas for a two and five minute travel time are used. Barriers can also be added which can effect the service area by not letting traffic through and adding to the time to get to locations.",
        "-To add a facility, click the facility button, then click anywhere on the MapView.\n-To add a barrier, click the barrier button, and click multiple locations on MapView.\n-Double tap on the MapView to finish drawing the barrier.\n-To show service areas around facilities that were added, click the show service areas button.\n-Click the reset button to clear all graphics and features.",
        "ArcGISMap, GraphicsOverlay, MapView, PolylineBarrier, ServiceAreaFacility, ServiceAreaParameters, ServiceAreaPolygon, ServiceAreaResult, ServiceAreaTask, SketchEditor")]
    public partial class FindServiceArea
    {
        // Uri for the service area around San Diego.
        private Uri _serviceAreaUri = new Uri("https://sampleserver6.arcgisonline.com/arcgis/rest/services/NetworkAnalysis/SanDiego/NAServer/ServiceArea");

        public FindServiceArea()
        {
            InitializeComponent();

            // Create the map, graphics overlay, and sketch editor.
            Initialize();
        }

        private void Initialize()
        {
            // Center the map on San Diego.
            Map streetsMap = new Map(Basemap.CreateLightGrayCanvasVector())
            {
                InitialViewpoint = new Viewpoint(32.73, -117.14, 30000)
            };
            MyMapView.Map = streetsMap;

            // Create graphics overlays for all of the elements of the map.
            MyMapView.GraphicsOverlays.Add(new GraphicsOverlay());

            // Add a new behavior for double taps on the MapView.
            MyMapView.GeoViewDoubleTapped += (s, e) =>
            {
                // If the sketch editor complete command is enabled, a sketch is in progress.
                if (MyMapView.SketchEditor.CompleteCommand.CanExecute(null))
                {
                    // Set the event as handled.
                    e.Handled = true;

                    // Finish any drawing.
                    MyMapView.SketchEditor.CompleteCommand.Execute(null);

                    // Reset the UI.
                    DrawBarrierButton.Text = "Draw barrier";
                }
            };
        }

        private async void PlaceFacilityButton_Click(object sender, EventArgs e)
        {
            try
            {
                // Let the user tap on the map view using the point sketch mode.
                SketchCreationMode creationMode = SketchCreationMode.Point;
                Geometry geometry = await MyMapView.SketchEditor.StartAsync(creationMode, false);

                // Symbology for a facility.
                PictureMarkerSymbol facilitySymbol = new PictureMarkerSymbol(new Uri("https://static.arcgis.com/images/Symbols/SafetyHealth/Hospital.png"))
                {
                    Height = 30,
                    Width = 30
                };

                // Create a graphic for the facility.
                Graphic facilityGraphic = new Graphic(geometry, new Dictionary<string, object>() { { "Type", "Facility" } }, facilitySymbol)
                {
                    ZIndex = 2
                };

                // Add the graphic to the graphics overlay.
                MyMapView.GraphicsOverlays[0].Graphics.Add(facilityGraphic);
            }
            catch (TaskCanceledException)
            {
                // Ignore this exception.
            }
            catch (Exception ex)
            {
                // Report exceptions.
                await Application.Current.MainPage.DisplayAlert("Error", "Error drawing facility:\n" + ex.Message, "OK");
            }
        }

        private async void DrawBarrierButton_Click(object sender, EventArgs e)
        {
            // Finish drawing barriers if started.
            if (DrawBarrierButton.Text != "Draw barrier")
            {
                if (MyMapView.SketchEditor.CompleteCommand.CanExecute(null))
                    MyMapView.SketchEditor.CompleteCommand.Execute(null);

                DrawBarrierButton.Text = "Draw barrier";
                return;
            }
            try
            {
                // Update the UI.
                DrawBarrierButton.Text = "Finish drawing";

                // Let the user draw on the map view using the polyline sketch mode.
                SketchCreationMode creationMode = SketchCreationMode.Polyline;
                Geometry geometry = await MyMapView.SketchEditor.StartAsync(creationMode, false);

                // Symbol for the barriers.
                SimpleLineSymbol barrierSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, System.Drawing.Color.Black, 5.0f);

                // Create the graphic to be used for barriers.
                Graphic barrierGraphic = new Graphic(geometry, new Dictionary<string, object>() { { "Type", "Barrier" } }, barrierSymbol)
                {
                    ZIndex = 1
                };

                // Add a graphic from the polyline the user drew.
                MyMapView.GraphicsOverlays[0].Graphics.Add(barrierGraphic);
            }
            catch (TaskCanceledException)
            {
                // Ignore this exception.
            }
            catch (Exception ex)
            {
                // Report exceptions.
                await Application.Current.MainPage.DisplayAlert("Error", "Error drawing barrier:\n" + ex.Message, "OK");
            }
        }

        private async void ShowServiceAreasButton_Click(object sender, EventArgs e)
        {
            // Finish any drawing in progress.
            if (MyMapView.SketchEditor.CompleteCommand.CanExecute(null))
            {
                MyMapView.SketchEditor.CompleteCommand.Execute(null);

                DrawBarrierButton.Text = "Draw barrier";
            }

            // Use a local variable for the graphics overlay.
            GraphicCollection allGraphics = MyMapView.GraphicsOverlays[0].Graphics;

            // Get a list of the facilities from the graphics overlay.
            List<ServiceAreaFacility> serviceAreaFacilities = (from g in allGraphics
                                                               where (string)g.Attributes["Type"] == "Facility"
                                                               select new ServiceAreaFacility((MapPoint)g.Geometry)).ToList();

            // Check that there is at least 1 facility to find a service area for.
            if (!serviceAreaFacilities.Any())
            {
                await Application.Current.MainPage.DisplayAlert("Error", "Must have at least one Facility!", "OK");
                return;
            }

            // Create the service area task and parameters based on the Uri.
            ServiceAreaTask serviceAreaTask = await ServiceAreaTask.CreateAsync(_serviceAreaUri);

            // Store the default parameters for the service area in an object.
            ServiceAreaParameters serviceAreaParameters = await serviceAreaTask.CreateDefaultParametersAsync();

            // Add impedance cutoffs for facilities (drive time minutes).
            serviceAreaParameters.DefaultImpedanceCutoffs.Add(2.0);
            serviceAreaParameters.DefaultImpedanceCutoffs.Add(5.0);

            // Set the level of detail for the polygons.
            serviceAreaParameters.PolygonDetail = ServiceAreaPolygonDetail.High;

            // Get a list of the barriers from the graphics overlay.
            List<PolylineBarrier> polylineBarriers = (from g in allGraphics
                                                      where (string)g.Attributes["Type"] == "Barrier"
                                                      select new PolylineBarrier((Polyline)g.Geometry)).ToList();

            // Add the barriers to the service area parameters.
            serviceAreaParameters.SetPolylineBarriers(polylineBarriers);

            // Update the parameters to include all of the placed facilities.
            serviceAreaParameters.SetFacilities(serviceAreaFacilities);

            // Clear existing graphics for service areas.
            foreach (Graphic g in allGraphics.ToList())
            {
                // Check if the graphic g is a service area.
                if ((string)g.Attributes["Type"] == "ServiceArea")
                {
                    allGraphics.Remove(g);
                }
            }

            try
            {
                // Solve for the service area of the facilities.
                ServiceAreaResult result = await serviceAreaTask.SolveServiceAreaAsync(serviceAreaParameters);

                // Loop over each facility.
                for (int i = 0; i < serviceAreaFacilities.Count; i++)
                {
                    // Create list of polygons from a service facility.
                    List<ServiceAreaPolygon> polygons = result.GetResultPolygons(i).ToList();

                    // Symbol for the outline of the service areas.
                    SimpleLineSymbol serviceOutline = new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, System.Drawing.Color.DarkGray, 3.0f);

                    // Create a list of fill symbols for the polygons.
                    List<SimpleFillSymbol> fillSymbols = new List<SimpleFillSymbol>();
                    fillSymbols.Add(new SimpleFillSymbol(SimpleFillSymbolStyle.Solid, System.Drawing.Color.FromArgb(70, 255, 0, 0), serviceOutline));
                    fillSymbols.Add(new SimpleFillSymbol(SimpleFillSymbolStyle.Solid, System.Drawing.Color.FromArgb(70, 255, 165, 0), serviceOutline));

                    // Loop over every polygon in every facilities result.
                    for (int j = 0; j < polygons.Count; j++)
                    {
                        // Create the graphic for the service areas, alternating between fill symbols.
                        Graphic serviceGraphic = new Graphic(polygons[j].Geometry, new Dictionary<string, object>() { { "Type", "ServiceArea" } }, fillSymbols[j % 2])
                        {
                            ZIndex = 0
                        };

                        // Add graphic for service area. Alternate the color of each polygon.
                        allGraphics.Add(serviceGraphic);
                    }
                }
            }
            catch (Esri.ArcGISRuntime.Http.ArcGISWebException exception)
            {
                if (exception.Message.ToString().Equals("Unable to complete operation."))
                {
                    await Application.Current.MainPage.DisplayAlert("Error", "Facility not within San Diego area!", "OK");
                }
                else
                {
                    await Application.Current.MainPage.DisplayAlert("Error", "An ArcGIS web exception occurred. \n" + exception.Message, "OK");
                }
            }
        }

        private void Reset_Click(object sender, EventArgs e)
        {
            // Clear all of the graphics.
            MyMapView.GraphicsOverlays[0].Graphics.Clear();
        }
    }
}
XAML
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:esriUI="clr-namespace:Esri.ArcGISRuntime.Xamarin.Forms;assembly=Esri.ArcGISRuntime.Xamarin.Forms"
             x:Class="ArcGISRuntime.Samples.FindServiceArea.FindServiceArea"
             Title="Find service area (interactive)">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="auto" />
            <RowDefinition Height="auto" />
            <RowDefinition Height="auto" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>
        <Button x:Name="PlaceFacilityButton"
                        Grid.Row="0" Grid.Column="0"
                        Text="Place Facility"
                        Clicked="PlaceFacilityButton_Click"
                        HorizontalOptions="FillAndExpand" />
        <Button x:Name="DrawBarrierButton"
                        Grid.Row="0" Grid.Column="1"
                        Text="Draw Barrier"
                        Clicked="DrawBarrierButton_Click"
                        HorizontalOptions="FillAndExpand" />
        <Button x:Name="ShowServiceAreasButton"
                        Grid.Row="1"
                        Grid.ColumnSpan="2"
                        Text="Show Service Areas"
                        Clicked="ShowServiceAreasButton_Click"
                        HorizontalOptions="FillAndExpand" />
        <Button x:Name="ResetButton"
                        Grid.Row="2"
                        Grid.ColumnSpan="2"
                        Text="Reset"
                        Clicked="Reset_Click"
                        HorizontalOptions="FillAndExpand" />
        <esriUI:MapView x:Name="MyMapView"  
                        Grid.Row="3" 
                        Grid.ColumnSpan="2"/>
    </Grid>
</ContentPage>
See Also
Additional Examples
Hyperlink to ExampleDescription
FindServiceAreaFind the service area within a network from a given point.