Show location history

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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
    }
}