Display Device Location

Learn how to display the current device location on a map or scene.

display device location

You can display the device location on a map or scene. This is important for workflows that require the user's current location, such as finding nearby businesses, navigating from the current location, or identifying and collecting geospatial information.

By default, location display uses the device's location provider. Your app can also process input from other location providers, such as an external GPS receiver or a provider that returns a simulated location. For more information, see the Show device location topic.

Prerequisites

The following are required for this tutorial:

  1. An ArcGIS account to access your API keys. If you don't have an account, sign up for free.
  2. Your system meets the system requirements.

Steps

Open the Xcode project

  1. To start the tutorial, complete the Display a map tutorial or download and unzip the solution.

  2. Open the .xcodeproj file in Xcode.

  3. If you downloaded the solution project, set your API key.

    An API Key enables access to services, web maps, and web scenes hosted in ArcGIS Online.

    1. Go to your developer dashboard to get your API key. For these tutorials, use your default API key. It is scoped to include all of the services demonstrated in the tutorials.

    2. In Xcode, in the Project Navigator, click MainApp.swift.
    3. In the Editor, set the ArcGISEnvironment.apiKey property on the ArcGISEnvironment with your API key.

    MainApp.swift
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    import SwiftUI
    
    import ArcGIS
    
    @main
    struct MainApp: App {
    
        init() {
            ArcGISEnvironment.apiKey = APIKey("<#your-API-key#>")
        }
    
        var body: some SwiftUI.Scene {
            WindowGroup {
                ContentView()
    
                    .ignoresSafeArea()
    
            }
        }
    
    }

Add a custom iOS target property

The app must provide a message that tells the user why the app is requesting access to the user's location when the app is in use.

  1. In Xcode, in the Project navigator, select the target app.

  2. Click the Info tab and add the "Privacy - Location When In Use Usage Description" key under Custom iOS Target Properties.

  3. Add a string value describing how the app would use the device location. For example, "Your location is used to show your position on the map."

    To learn more about requesting user authorization, see the Note in the Location data sources section of the Device location guide topic.

Import Core Location

  1. In Xcode, in the Project Navigator, click ContentView.swift.

  2. In the Editor, import the CoreLocation framework. This is required to request the user's location.

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import ArcGIS

import CoreLocation

Initialize the map

  1. The map will zoom to the extent of the current location, so you don't need to set the viewpoint anymore. Remove the map StateObject and replace it with just a map initializer.

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    struct ContentView: View {
    
        private let map = Map(basemapStyle: .arcGISTopographic)
    
    

Add location display to map view

  1. Create the location display using the system location data source.

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    struct ContentView: View {
    
        private let map = Map(basemapStyle: .arcGISTopographic)
    
        private let locationDisplay = LocationDisplay(dataSource: SystemLocationDataSource())
    
    
  2. Add the location display modifier to the map view.

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        var body: some View {
            MapView(map: map)
    
                .locationDisplay(locationDisplay)
    
                }
    
        }
    

Request user authorization to use location

The app must request authorization from the user to access the device location. The user can grant or deny the request.

  1. In the task modifier, create a CLLocationManager.

  2. If the authorization status is not determined, request "in use authorization".

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        var body: some View {
            MapView(map: map)
    
                .locationDisplay(locationDisplay)
    
                .task {
                    let locationManager = CLLocationManager()
                    if locationManager.authorizationStatus == .notDetermined {
                        locationManager.requestWhenInUseAuthorization()
                    }
    
                }
    
        }
    

Show the current location

A map view provides LocationDisplay for showing the current location of the device. The location symbol is displayed on top of all content in the map view.

Instances of this class manage the display of device location on a map view: the symbols, animation, auto pan behavior, and so on. Location display is an overlay of the map view, and displays above everything else, including graphics overlays.

The location display does not retrieve location information, that is the job of the associated data source, which provides location updates on a regular basis. In addition to the default system location data source, you can use location providers based on external GPS devices or a simulated location source.

Each map view has its own instance of a location display and instances of location display and location data source are not shared by multiple map views. This allows you to start and stop location display independently on multiple map views without affecting each other.

  1. Start displaying the location by calling the data source's start() method.

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        var body: some View {
            MapView(map: map)
    
                .locationDisplay(locationDisplay)
    
                .task {
                    let locationManager = CLLocationManager()
                    if locationManager.authorizationStatus == .notDetermined {
                        locationManager.requestWhenInUseAuthorization()
                    }
    
                    do {
                        try await locationDisplay.dataSource.start()
    
                    } catch {
    
                    }
    
                }
    
        }
    
  2. Set the initial zoom scale and the auto pan mode.

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        var body: some View {
            MapView(map: map)
    
                .locationDisplay(locationDisplay)
    
                .task {
                    let locationManager = CLLocationManager()
                    if locationManager.authorizationStatus == .notDetermined {
                        locationManager.requestWhenInUseAuthorization()
                    }
    
                    do {
                        try await locationDisplay.dataSource.start()
    
                        locationDisplay.initialZoomScale = 40_000
                        locationDisplay.autoPanMode = .recenter
    
                    } catch {
    
                    }
    
                }
    
        }
    

Error handling

  1. Add a Bool called failedToStart.

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    struct ContentView: View {
    
        private let map = Map(basemapStyle: .arcGISTopographic)
    
        private let locationDisplay = LocationDisplay(dataSource: SystemLocationDataSource())
    
        @State private var failedToStart = false
    
  2. In the catch closure, set the failedToStart boolean to true. If the location display fails to start, the value will be changed.

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                    do {
                        try await locationDisplay.dataSource.start()
    
                        locationDisplay.initialZoomScale = 40_000
                        locationDisplay.autoPanMode = .recenter
    
                    } catch {
    
                        self.failedToStart = true
    
                    }
    
  3. Present an alert if the location display failed to start.

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        var body: some View {
            MapView(map: map)
    
                .locationDisplay(locationDisplay)
    
                .task {
                    let locationManager = CLLocationManager()
                    if locationManager.authorizationStatus == .notDetermined {
                        locationManager.requestWhenInUseAuthorization()
                    }
    
                    do {
                        try await locationDisplay.dataSource.start()
    
                        locationDisplay.initialZoomScale = 40_000
                        locationDisplay.autoPanMode = .recenter
    
                    } catch {
    
                        self.failedToStart = true
    
                    }
    
                }
    
                .alert("Location display failed to start", isPresented: $failedToStart) {}
    
        }
    
    Expand

Run the app

  1. Press <Command+R> to run the app.

    If you are using the Xcode simulator your system must meet these minimum requirements: macOS Big Sur 11.3, Xcode 13.4, iOS 14.0. If you are using a physical device, then refer to the system requirements.

  2. When the app runs, you'll see the system prompt requesting to use the device location. Tap to either Allow once or While using the app.

  3. If the app is running on a simulator, you'll have to provide a simulated location. Go to the Features menu of the Simulator. Under Location, choose a predefined option or enter a custom Location.

Your map should now show the device's location, either simulated or actual.

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