Show location history

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Sample viewer app

Display your location history on the map.

Image of Show location history

Use case

You can track device location history and display it as lines and points on the map. The history can be used to visualize how the user moved through the world, to retrace their steps, or to create new feature geometry. An unmapped trail, for example, could be added to the map using this technique.

How to use the sample

Tap "Start tracking" to start tracking your location, which will appear as points on the map. A line will connect the points for easier visualization. Tap "Stop tracking" to stop updating the location history. This sample uses a simulated data source. To track a user's real position, use the default location data source instead.

How it works

  1. If necessary, request location permission from the operating system.
  2. Create a graphics overlay to show each point and another graphics overlay for displaying the route line.
  3. Create an instance of AGSSimulatedLocationDataSource and initialize it with a polyline, and start receiving location updates.
  4. NOTE: To track a user's real position, use the default location data source for location display instead.
  5. Specify a locationChangedHandler on AGSLocationDisplay to handle location updates.
  6. Every time the location updates, store that location, display a point on the map, and recreate the route line.

Relevant API

  • AGSCLLocationDataSource
  • AGSGraphic
  • AGSGraphicsOverlay
  • AGSLocationDataSource
  • AGSLocationDisplay
  • AGSMap
  • AGSMapView
  • AGSPolylineBuilder
  • AGSSimpleLineSymbol
  • AGSSimpleMarkerSymbol
  • AGSSimpleRenderer
  • AGSSimulatedLocationDataSource

About the data

The sample uses a light gray vector basemap. The default data source relies on Core Location, which works with either device sensors or location simulation.

A custom set of points is used to create an AGSPolyline and initialize an AGSSimulatedLocationDataSource. This simulated location data source enables easier testing and allows the sample to be used on devices without an actively updating GPS signal.

Tags

bread crumb, breadcrumb, GPS, history, movement, navigation, real-time, trace, track, trail

Sample Code

LocationHistoryViewController.swift
                                                                                                                                                                                                                                    
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//
// 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.
//

import UIKit
import ArcGIS

// MARK: - Constants

private enum Constants {
    static let locationBorderColor = UIColor.white
    static let locationInnerColor = UIColor.black
    static let trackColor = UIColor.accentColor.withAlphaComponent(0.5)
    static let locationDiameter: CGFloat = 14
    static let locationBorderWidth: CGFloat = 2
    static let trackWidth: CGFloat = 10

    static let initialZoomScale: Double = 10000
}

// MARK: - LocationHistoryViewController

class LocationHistoryViewController: UIViewController {
    @IBOutlet private weak var mapView: AGSMapView!
    @IBOutlet private weak var trackingBarButtonItem: UIBarButtonItem! {
        didSet {
            trackingBarButtonItem.possibleTitles = [
                "Start tracking",
                "Stop tracking"
            ]
        }
    }

    private let polylineJSONString = """
    {"paths":[[ [-13185646.046666779,4037971.5966668758],
    [-13185586.780000051,4037827.6633333955],[-13185514.813333312,4037709.1299999417],
    [-13185569.846666701,4037522.8633330846],[-13185591.01333339,4037378.9299996048],
    [-13185629.113333428,4037283.6799995075],[-13185770.93000024,4037425.4966663187],
    [-13185821.730000293,4037546.146666442],[-13185880.996667018,4037704.8966666036],
    [-13185948.730000421,4037874.2300001099],[-13185974.130000448,4037946.1966668498],
    [-13186120.180000596,4037958.896666863],[-13186264.113334076,4037984.296666889],
    [-13186336.080000836,4038001.2300002342],[-13186314.91333415,4037757.8133333195],
    [-13186272.580000773,4037560.9633331187],[-13186187.913334005,4037463.59666635],
    [-13186431.33000092,4037404.3299996229],[-13186676.863334503,4037290.0299995062],
    [-13187625.130002158,4038589.6633341513],[-13187333.030001862,4038756.8800009824],
    [-13187091.730001617,4038617.1800008402],[-13186791.163334643,4038805.5633343654],
    [-13186721.313334571,4038801.3300010278],[-13186833.49666802,4038195.9633337436],
    [-13186977.677439401,4037699.8176972247],[-13186784.921301765,4037820.4541915278],
    [-13186749.517113185,4038150.8932846226],[-13186649.860878762,4038288.5762400767],
    [-13186556.760975549,4038323.9804286221],[-13186472.839936033,4038481.3323777127],
    [-13186373.183701571,4038489.1999751539],[-13186344.335844241,4038242.6819215398],
    [-13186126.665647998,4038308.245233661],[-13185814.584282301,4038358.0733508728],
    [-13185651.987268206,4038116.8003622484],[-13185203.534213299,4038048.6145176427],
    [-13184576.748949422,4038150.8932845518],[-13184251.55492135,4037833.5668537691],
    [-13184146.653621957,4037524.1080205571],[-13183949.963685593,4037621.1417224966],
    [-13183687.71043711,4037781.1162040718],[-13183480.530370807,4037875.5273735262],
    [-13182307.629999243,4037859.7460188437],[-13181376.039484169,4037820.9297473822],
    [-13180716.162869323,4038364.3575478429],[-13180182.439136729,4038810.7446696493],
    [-13178474.523192419,4040237.2426458625],[-13178321.134040033,4039740.6894803117],
    [-13177958.020228144,4039140.1550991111],[-13177073.512224896,4037459.5898928214],
    [-13177757.842101147,4037589.9384406791],[-13178386.308314031,4037799.427178307],
    [-13180095.012208173,4037811.6550856642],[-13180126.165447287,4036845.9046731163],
    [-13179806.844746364,4036324.0879179495],[-13180928.361354485,4035887.9425703473],
    [-13181598.155995468,4035428.432293402],[-13182984.47513606,4034447.105261297],
    [-13182229.264383668,4033222.8051626245],[-13182058.735615831,4033339.8690072047],
    [-13181939.035180708,4033691.2477038498],[-13182116.65518121,4033861.1450956347],
    [-13181792.305615077,4034085.1007484416],[-13182027.845180977,4034467.3698799671],
    [-13181877.254310986,4034644.9898804692],[-13181630.130832028,4034517.5668366305],
    [-13181386.868657427,4034424.8955320208],[-13181228.555178719,4034652.7124891868],
    [-13181379.14604871,4034942.3103160923],[-13181267.168222306,4035189.4337950516],
    [-13181074.103004368,4035015.6750989081],[-13180807.673003616,4034934.5877073747],
    [-13180618.469090037,4034814.8872722536],[-13180599.162568243,4035374.7764042714],
    [-13181047.073873857,4035494.476839392],[-13181317.365178969,4035413.3894478586],
    [-13180765.198655669,4035143.0981427468],[-13180328.871263131,4034892.1133594285],
    [-13180270.951697765,4035258.9372735149],[-13180325.009958787,4035718.4324922049],
    [-13180707.279090302,4035695.2646660525],[-13181413.897788007,4035536.9511873648],
    [-13181618.54691902,4035807.2424924765],[-13181884.976919774,4036065.949884512],
    [-13182159.129529245,4035861.3007534989],[-13182174.57474668,4035668.2355355616],
    [-13182417.83692128,4035664.374231203],[-13182784.660835361,4035409.5281435261],
    [-13182997.032575091,4035255.0759691764],[-13182618.624747934,4034679.7416197238]
    ]],"spatialReference":{"wkid":102100,"latestWkid":3857}}
    """

    private var isTracking = false {
        didSet {
            handleLocationStatusChange()
        }
    }

    private var locationGraphic = AGSGraphic()
    private var trackGraphic = AGSGraphic()

    private var trackBuilder: AGSPolylineBuilder?
    private var pointBuilder: AGSMultipointBuilder?

    private var lastPosition: AGSPoint?

    // MARK: UIViewController

    override func viewDidLoad() {
        super.viewDidLoad()
        // Add the source code button item to the right of navigation bar.
        (self.navigationItem.rightBarButtonItem as? SourceCodeBarButtonItem)?.filenames = ["LocationHistoryViewController"]
        setupMapView()
    }

    // MARK: IBActions

    @IBAction private func trackingTapped(_ sender: UIBarButtonItem) {
        isTracking.toggle()
    }

    // MARK: Private behavior

    private func makeDataSource(polylineJSONString: String) -> AGSSimulatedLocationDataSource {
        let simulatedDataSource = AGSSimulatedLocationDataSource()
        do {
            let jsonObject = try JSONSerialization.jsonObject(with: polylineJSONString.data(using: .utf8)!)
            let routePolyline = try AGSPolyline.fromJSON(jsonObject) as! AGSPolyline
            let densifiedRoute = AGSGeometryEngine.geodeticDensifyGeometry(
                routePolyline,
                maxSegmentLength: 50.0,
                lengthUnit: .meters(),
                curveType: .geodesic
            )
            simulatedDataSource.setLocationsWith(densifiedRoute as! AGSPolyline)
        } catch {
            presentAlert(error: error)
        }
        return simulatedDataSource
    }

    private func makeOverlay(rendererSymbol: AGSSymbol) -> AGSGraphicsOverlay {
        let overlay = AGSGraphicsOverlay()
        overlay.renderer = AGSSimpleRenderer(symbol: rendererSymbol)
        return overlay
    }

    private func handleLocationStatusChange() {
        if isTracking {
            startProcessingLocationChanges()
        } else {
            stopProcessingLocationChanges()
        }
        updateView()
    }

    private func processLocationUpdate() {
        guard isTracking, let position = lastPosition, position.x != 0, position.y != 0 else { return }
        pointBuilder?.points.add(position)
        locationGraphic.geometry = pointBuilder?.toGeometry()
        trackBuilder?.add(position)
        trackGraphic.geometry = trackBuilder?.toGeometry()
    }

    private func setupLocationDisplay(_ locationDisplay: AGSLocationDisplay) {
        locationDisplay.autoPanMode = .recenter
        locationDisplay.initialZoomScale = Constants.initialZoomScale
        // Comment out the line below to use device live location.
        locationDisplay.dataSource = makeDataSource(polylineJSONString: polylineJSONString)

        locationDisplay.start { [weak self] (error) in
            if let error = error {
                self?.presentAlert(error: error)
            }
        }
    }

    private func setupMapView() {
        let map = AGSMap(basemapStyle: .arcGISLightGrayBase)
        mapView.map = map
        map.load { [weak self, unowned map] (_) in
            guard let self = self else { return }
            let spatialReference = map.spatialReference
            self.pointBuilder = AGSMultipointBuilder(spatialReference: spatialReference)
            self.trackBuilder = AGSPolylineBuilder(spatialReference: spatialReference)
        }

        let trackSymbol = AGSSimpleLineSymbol(style: .solid, color: Constants.trackColor, width: Constants.trackWidth)
        let trackOverlay = makeOverlay(rendererSymbol: trackSymbol)
        trackOverlay.graphics.add(trackGraphic)

        let locationSymbol = AGSSimpleMarkerSymbol(style: .circle, color: Constants.locationInnerColor, size: Constants.locationDiameter)
        locationSymbol.outline = AGSSimpleLineSymbol(style: .solid, color: Constants.locationBorderColor, width: Constants.locationBorderWidth)
        let locationsOverlay = makeOverlay(rendererSymbol: locationSymbol)
        locationsOverlay.graphics.add(locationGraphic)

        mapView.graphicsOverlays.addObjects(from: [trackOverlay, locationsOverlay])
        setupLocationDisplay(mapView.locationDisplay)
        updateView()
    }

    private func startProcessingLocationChanges() {
        mapView.locationDisplay.locationChangedHandler = { [weak self] (location) in
            guard let self = self, location.horizontalAccuracy >= 0 else { return }
            DispatchQueue.main.async {
                self.processLocationUpdate()
                self.lastPosition = location.position
            }
        }
    }

    private func stopProcessingLocationChanges() {
        mapView.locationDisplay.locationChangedHandler = nil
    }

    private func updateView() {
        let buttonText: String
        if isTracking {
            buttonText = "Stop tracking"
        } else {
            buttonText = "Start tracking"
        }
        trackingBarButtonItem.title = buttonText
    }
}

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