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dpearson2699/swift-ios-skills

Agent skills for iOS, iPadOS, Swift, SwiftUI, and modern Apple framework development.

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SKILL.mdskills/mapkit/

name:
mapkit
description:
Implement, review, or improve maps and location features in iOS/macOS apps using MapKit and CoreLocation. Use when working with Map views, annotations, markers, polylines, user location tracking, geocoding, reverse geocoding, search/autocomplete, directions and routes, geofencing, region monitoring, CLLocationUpdate async streams, or location authorization flows. Also use when working with maps, coordinates, addresses, places, directions, distance calculations, or location-based features in Swift apps.

MapKit

Build map-based and location-aware features targeting iOS 17+ with SwiftUI MapKit and modern CoreLocation async APIs. Use Map with MapContentBuilder for views, CLLocationUpdate.liveUpdates() for streaming location, and CLMonitor for geofencing.

Read references/mapkit-patterns.md when you need full map setup, search, routes, Look Around, snapshots, or iOS 26 place APIs. Read references/mapkit-corelocation-patterns.md when the task involves location update lifecycle, geofencing, background location, testing, or privacy keys.

Contents

  • Workflow
  • SwiftUI Map View (iOS 17+)
  • CoreLocation Modern API
  • Geocoding
  • Search
  • Directions
  • PlaceDescriptor (iOS 26+)
  • Common Mistakes
  • Review Checklist
  • References

Workflow

1. Add a map with markers or annotations

  1. Import MapKit.
  2. Create a Map view with optional MapCameraPosition binding.
  3. Add Marker, Annotation, MapPolyline, MapPolygon, or MapCircle inside the MapContentBuilder closure.
  4. Configure map style with .mapStyle().
  5. Add map controls with .mapControls { }.
  6. Handle selection with a selection: binding.

2. Track user location

  1. Add NSLocationWhenInUseUsageDescription to Info.plist.
  2. On iOS 18+, create a CLServiceSession to manage authorization.
  3. Iterate CLLocationUpdate.liveUpdates() in a Task.
  4. Filter updates by distance or accuracy before updating the UI.
  5. Stop the task when location tracking is no longer needed.

3. Search for places

  1. Configure MKLocalSearchCompleter for autocomplete suggestions.
  2. Debounce user input (at least 300ms) before setting the query.
  3. Convert selected completion to MKLocalSearch.Request for full results.
  4. Display results as markers or in a list.

4. Get directions and display a route

  1. Create an MKDirections.Request with source and destination MKMapItem.
  2. Set transportType (.automobile, .walking, .transit, .cycling).
  3. Await MKDirections.calculate().
  4. Draw the route with MapPolyline(route.polyline).

5. Review existing map/location code

Run through the Review Checklist at the end of this file.

SwiftUI Map View (iOS 17+)

import MapKit
import SwiftUI

struct PlaceMap: View {
    @State private var position: MapCameraPosition = .automatic

    var body: some View {
        Map(position: $position) {
            Marker("Apple Park", coordinate: applePark)
            Marker("Infinite Loop", systemImage: "building.2",
                   coordinate: infiniteLoop)
        }
        .mapStyle(.standard(elevation: .realistic))
        .mapControls {
            MapUserLocationButton()
            MapCompass()
            MapScaleView()
        }
    }
}

Marker and Annotation

// Balloon marker -- simplest way to pin a location
Marker("Cafe", systemImage: "cup.and.saucer.fill", coordinate: cafeCoord)
    .tint(.brown)

// Annotation -- custom SwiftUI view at a coordinate
Annotation("You", coordinate: userCoord, anchor: .bottom) {
    Image(systemName: "figure.wave")
        .padding(6)
        .background(.blue.gradient, in: .circle)
        .foregroundStyle(.white)
}

Overlays: Polyline, Polygon, Circle

Map {
    // Polyline from coordinates
    MapPolyline(coordinates: routeCoords)
        .stroke(.blue, lineWidth: 4)

    // Polygon (area highlight)
    MapPolygon(coordinates: parkBoundary)
        .foregroundStyle(.green.opacity(0.3))
        .stroke(.green, lineWidth: 2)

    // Circle (radius around a point)
    MapCircle(center: storeCoord, radius: 500)
        .foregroundStyle(.red.opacity(0.15))
        .stroke(.red, lineWidth: 1)
}

Camera Position

MapCameraPosition controls what the map displays. Bind it to let the user interact and to programmatically move the camera.

// Center on a region
@State private var position: MapCameraPosition = .region(
    MKCoordinateRegion(
        center: CLLocationCoordinate2D(latitude: 37.334, longitude: -122.009),
        span: MKCoordinateSpan(latitudeDelta: 0.05, longitudeDelta: 0.05)
    )
)

// Follow user location
@State private var position: MapCameraPosition = .userLocation(fallback: .automatic)

// Specific camera angle (3D perspective)
@State private var position: MapCameraPosition = .camera(
    MapCamera(centerCoordinate: applePark, distance: 1000, heading: 90, pitch: 60)
)

// Frame specific items
position = .item(MKMapItem.forCurrentLocation())
position = .rect(MKMapRect(...))

Map Style

.mapStyle(.standard)                                        // Default road map
.mapStyle(.standard(elevation: .realistic, showsTraffic: true))
.mapStyle(.imagery)                                         // Satellite
.mapStyle(.imagery(elevation: .realistic))                  // 3D satellite
.mapStyle(.hybrid)                                          // Satellite + labels
.mapStyle(.hybrid(elevation: .realistic, showsTraffic: true))

Map Interaction Modes

.mapInteractionModes(.all)           // Default: pan, zoom, rotate, pitch
.mapInteractionModes(.pan)           // Pan only
.mapInteractionModes([.pan, .zoom])  // Pan and zoom
.mapInteractionModes([])             // Static map (no interaction)

Map Selection

@State private var selectedMarker: MKMapItem?

Map(selection: $selectedMarker) {
    ForEach(places) { place in
        Marker(place.name, coordinate: place.coordinate)
            .tag(place.mapItem)     // Tag must match selection type
    }
}
.onChange(of: selectedMarker) { _, newValue in
    guard let item = newValue else { return }
    // React to selection
}

CoreLocation Modern API

CLLocationUpdate.liveUpdates() (iOS 17+)

Replace CLLocationManagerDelegate callbacks with a single async sequence. Each iteration yields a CLLocationUpdate containing an optional CLLocation. On iOS 18+, handle diagnostic states such as denied authorization, globally disabled Location Services, unavailable location, and insufficient in-use conditions with a visible degraded path instead of silently waiting forever. Store the task so the feature can cancel it, and reject invalid, inaccurate, stale, or unusable movement data before driving map UI or background work.

import CoreLocation

@MainActor
@Observable
final class LocationTracker {
    var currentLocation: CLLocation?
    private var updateTask: Task<Void, Never>?

    func startTracking() {
        updateTask = Task {
            do {
                let updates = CLLocationUpdate.liveUpdates()
                for try await update in updates {
                    guard let location = update.location else { continue }
                    // Filter by horizontal accuracy
                    guard location.horizontalAccuracy >= 0,
                          location.horizontalAccuracy < 50 else { continue }
                    currentLocation = location
                }
            } catch is CancellationError {
                // Expected when tracking stops.
            } catch {
                currentLocation = nil
            }
        }
    }

    func stopTracking() {
        updateTask?.cancel()
        updateTask = nil
    }
}

CLServiceSession (iOS 18+)

Declare authorization requirements for a feature's lifetime. Hold a reference to the session for as long as you need location services.

// When-in-use authorization with full accuracy preference
let session = CLServiceSession(
    authorization: .whenInUse,
    fullAccuracyPurposeKey: "NearbySearchPurpose"
)
// Hold `session` as a stored property; release it when done.

On iOS 18+, CLLocationUpdate.liveUpdates() and CLMonitor take an implicit CLServiceSession if you do not create one explicitly. Create one explicitly when you need .always authorization or full accuracy.

Authorization Flow

// Info.plist keys (required):
// NSLocationWhenInUseUsageDescription
// NSLocationAlwaysAndWhenInUseUsageDescription (only if .always needed)

// Check authorization and guide user to Settings when denied
struct LocationPermissionView: View {
    @Environment(\.openURL) private var openURL

    var body: some View {
        ContentUnavailableView {
            Label("Location Access Denied", systemImage: "location.slash")
        } description: {
            Text("Enable location access in Settings to use this feature.")
        } actions: {
            Button("Open Settings") {
                if let url = URL(string: UIApplication.openSettingsURLString) {
                    openURL(url)
                }
            }
        }
    }
}

Geocoding

CLGeocoder (iOS 8+)

let geocoder = CLGeocoder()

// Forward geocoding: address string -> coordinates
let placemarks = try await geocoder.geocodeAddressString("1 Apple Park Way, Cupertino")
if let location = placemarks.first?.location {
    print(location.coordinate) // CLLocationCoordinate2D
}

// Reverse geocoding: coordinates -> placemark
let location = CLLocation(latitude: 37.3349, longitude: -122.0090)
let placemarks = try await geocoder.reverseGeocodeLocation(location)
if let placemark = placemarks.first {
    let address = [placemark.name, placemark.locality, placemark.administrativeArea]
        .compactMap { $0 }
        .joined(separator: ", ")
}

MKGeocodingRequest and MKReverseGeocodingRequest (iOS 26+)

New MapKit-native geocoding that returns MKMapItem with richer data and MKAddress / MKAddressRepresentations for flexible address formatting.

@available(iOS 26, *)
func reverseGeocode(location: CLLocation) async throws -> MKMapItem? {
    guard let request = MKReverseGeocodingRequest(location: location) else {
        return nil
    }
    let mapItems = try await request.mapItems
    return mapItems.first
}

@available(iOS 26, *)
func forwardGeocode(address: String) async throws -> [MKMapItem] {
    guard let request = MKGeocodingRequest(addressString: address) else { return [] }
    return try await request.mapItems
}

Search

MKLocalSearchCompleter (Autocomplete)

@Observable
final class SearchCompleter: NSObject, MKLocalSearchCompleterDelegate {
    var results: [MKLocalSearchCompletion] = []
    var query: String = "" { didSet { completer.queryFragment = query } }

    private let completer = MKLocalSearchCompleter()

    override init() {
        super.init()
        completer.delegate = self
        completer.resultTypes = [.address, .pointOfInterest]
    }

    func completerDidUpdateResults(_ completer: MKLocalSearchCompleter) {
        results = completer.results
    }

    func completer(_ completer: MKLocalSearchCompleter, didFailWithError error: Error) {
        results = []
    }
}

MKLocalSearch (Full Search)

func search(for completion: MKLocalSearchCompletion) async throws -> [MKMapItem] {
    let request = MKLocalSearch.Request(completion: completion)
    request.resultTypes = [.pointOfInterest, .address]
    let search = MKLocalSearch(request: request)
    let response = try await search.start()
    return response.mapItems
}

// Search by natural language query within a region
func searchNearby(query: String, region: MKCoordinateRegion) async throws -> [MKMapItem] {
    let request = MKLocalSearch.Request()
    request.naturalLanguageQuery = query
    request.region = region
    let search = MKLocalSearch(request: request)
    let response = try await search.start()
    return response.mapItems
}

Directions

func getDirections(from source: MKMapItem, to destination: MKMapItem,
                   transport: MKDirectionsTransportType = .automobile) async throws -> MKRoute? {
    let request = MKDirections.Request()
    request.source = source
    request.destination = destination
    request.transportType = transport
    let directions = MKDirections(request: request)
    let response = try await directions.calculate()
    return response.routes.first
}

Display Route on Map

@State private var route: MKRoute?

Map {
    if let route {
        MapPolyline(route.polyline)
            .stroke(.blue, lineWidth: 5)
    }
    Marker("Start", coordinate: startCoord)
    Marker("End", coordinate: endCoord)
}
.task {
    route = try? await getDirections(from: startItem, to: endItem)
}

ETA Calculation

func getETA(from source: MKMapItem, to destination: MKMapItem) async throws -> TimeInterval {
    let request = MKDirections.Request()
    request.source = source
    request.destination = destination
    let directions = MKDirections(request: request)
    let response = try await directions.calculateETA()
    return response.expectedTravelTime
}

Cycling Directions (iOS 14+)

func getCyclingDirections(to destination: MKMapItem) async throws -> MKRoute? {
    let request = MKDirections.Request()
    request.source = MKMapItem.forCurrentLocation()
    request.destination = destination
    request.transportType = .cycling
    let directions = MKDirections(request: request)
    let response = try await directions.calculate()
    return response.routes.first
}

PlaceDescriptor (iOS 26+)

Create rich place references from coordinates or addresses without needing a Place ID. Requires import GeoToolbox.

import GeoToolbox

@available(iOS 26, *)
func lookupPlace(name: String, coordinate: CLLocationCoordinate2D) async throws -> MKMapItem {
    let descriptor = PlaceDescriptor(
        representations: [.coordinate(coordinate)],
        commonName: name
    )
    let request = MKMapItemRequest(placeDescriptor: descriptor)
    return try await request.mapItem
}

Common Mistakes

DON'T: Request always authorization upfront. DO: Start with when-in-use authorization. On iOS 18+, hold a CLServiceSession for the feature lifetime; request .always only for background features that need system relaunch after termination.

DON'T: Use CLLocationManagerDelegate for simple location fetches on iOS 17+. DO: Use CLLocationUpdate.liveUpdates() async stream for cleaner, more concise code.

DON'T: Ignore CLLocationUpdate diagnostics such as denied, globally denied, or unavailable location. DO: Stop or degrade the feature, show recovery UI such as Settings guidance, and keep search/manual flows usable.

DON'T: Let liveUpdates() run from an unowned task after the map/view is gone. DO: Store the Task, cancel it when the feature stops, and filter invalid, inaccurate, stale, or impossible movement fixes.

DON'T: Force-unwrap CLPlacemark properties — they are all optional. DO: Use nil-coalescing: placemark.locality ?? "Unknown".

DON'T: Fire MKLocalSearchCompleter queries on every keystroke. DO: Debounce with .task(id: searchText) + Task.sleep(for: .milliseconds(300)).

DON'T: Silently fail when location authorization is denied. DO: Detect .denied status and show an alert with a Settings deep link.

DON'T: Assume geocoding always succeeds — handle empty results and network errors.

Review Checklist

  • Info.plist has NSLocationWhenInUseUsageDescription with specific reason
  • Authorization denial handled with Settings deep link
  • CLLocationUpdate task cancelled when not needed (battery)
  • Location accuracy appropriate for the use case
  • Map annotations use Identifiable data with stable IDs
  • Geocoding errors handled (network failure, no results)
  • Search completer input debounced
  • CLMonitor limited to 20 conditions, instance kept alive
  • Background location uses CLBackgroundActivitySession
  • Map tested with VoiceOver
  • Map annotation view models and location UI updates are @MainActor-isolated

References

skills

mapkit

SKILL.md

README.md

tile.json