141 lines
4.4 KiB
Markdown
141 lines
4.4 KiB
Markdown
# User Location & Location Privacy
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Requesting precise location with ``MLNLocationManager``.
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> Note: This example uses SwiftUI.
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This example shows how to request a precise location with ``MLNLocationManager``.
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Let's prepare your `Info.plist`:
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First, provide a description why your app needs to access location:
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```plist
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<key>NSLocationWhenInUseUsageDescription</key>
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<string>Dummy Location When In Use Description</string>
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```
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Second, add a description why your app needs precise location:
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```plist
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<key>NSLocationTemporaryUsageDescriptionDictionary</key>
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<dict>
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<key>MLNAccuracyAuthorizationDescription</key>
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<string>Dummy Precise Location Description</string>
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</dict>
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```
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Third and finally, specify your app only needs reduced location access by default (until you request precise accuracy in the example):
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```plist
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<key>NSLocationDefaultAccuracyReduced</key>
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<true/>
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```
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The `Coordinator` defined below is also the ``MLNMapViewDelegate``. When the location manager authorization changes it will call the relevant method. If precise location has not been granted, a button is shown at the bottom of the map.
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When the button is pressed a pop-up with the description we set in `Info.plist` will be shown:
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<!-- include-example(LocationPrivacyExample) -->
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```swift
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enum LocationAccuracyState {
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case unknown
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case reducedAccuracy
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case fullAccuracy
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}
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@MainActor
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class PrivacyExampleViewModel: NSObject, ObservableObject {
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@Published var locationAccuracy: LocationAccuracyState = .unknown
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@Published var showTemporaryLocationAuthorization = false
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}
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class PrivacyExampleCoordinator: NSObject, MLNMapViewDelegate {
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@ObservedObject private var mapViewModel: PrivacyExampleViewModel
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private var pannedToUserLocation = false
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init(mapViewModel: PrivacyExampleViewModel) {
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self.mapViewModel = mapViewModel
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super.init()
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}
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func mapView(_: MLNMapView, didChangeLocationManagerAuthorization manager: MLNLocationManager) {
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guard let accuracySetting = manager.accuracyAuthorization else {
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return
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}
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switch accuracySetting() {
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case .fullAccuracy:
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mapViewModel.locationAccuracy = .fullAccuracy
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case .reducedAccuracy:
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mapViewModel.locationAccuracy = .reducedAccuracy
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@unknown default:
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mapViewModel.locationAccuracy = .unknown
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}
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}
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// when a location is available for the first time, we fly to it
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func mapView(_ mapView: MLNMapView, didUpdate _: MLNUserLocation?) {
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guard !pannedToUserLocation else { return }
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guard let userLocation = mapView.userLocation else {
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print("User location is currently not available.")
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return
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}
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mapView.fly(to: MLNMapCamera(lookingAtCenter: userLocation.coordinate, altitude: 100_000, pitch: 0, heading: 0))
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pannedToUserLocation = true
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}
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}
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struct PrivacyExampleRepresentable: UIViewRepresentable {
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@ObservedObject var mapViewModel: PrivacyExampleViewModel
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func makeCoordinator() -> PrivacyExampleCoordinator {
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PrivacyExampleCoordinator(mapViewModel: mapViewModel)
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}
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func makeUIView(context: Context) -> MLNMapView {
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let mapView = MLNMapView()
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mapView.delegate = context.coordinator
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mapView.showsUserLocation = true
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return mapView
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}
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func updateUIView(_ mapView: MLNMapView, context _: Context) {
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if mapViewModel.showTemporaryLocationAuthorization {
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let purposeKey = "MLNAccuracyAuthorizationDescription"
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mapView.locationManager.requestTemporaryFullAccuracyAuthorization?(withPurposeKey: purposeKey)
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DispatchQueue.main.async {
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mapViewModel.showTemporaryLocationAuthorization = false
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}
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}
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}
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}
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struct LocationPrivacyExampleView: View {
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@StateObject private var viewModel = PrivacyExampleViewModel()
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var body: some View {
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VStack {
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PrivacyExampleRepresentable(mapViewModel: viewModel)
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.edgesIgnoringSafeArea(.all)
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if viewModel.locationAccuracy == LocationAccuracyState.reducedAccuracy {
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Button("Request Precise Location") {
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viewModel.showTemporaryLocationAuthorization.toggle()
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}
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.padding()
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.background(Color.blue)
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.foregroundColor(.white)
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.cornerRadius(8)
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}
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}
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}
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}
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```
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