Add scan flow MVP and local Axiom skill workspace

This snapshot establishes the camera-to-result recognition flow and related tests while checking in the project skill/docs assets required for the configured local tooling.
This commit is contained in:
Matthias
2026-04-19 21:11:32 +02:00
parent 577214d474
commit a60a76b797
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{
"source": "CharlesWiltgen/Axiom",
"sourceType": "git",
"repoUrl": "https://github.com/CharlesWiltgen/Axiom",
"subpath": "axiom-codex/skills/axiom-mapkit",
"installedAt": "2026-04-12T08:06:27.939Z"
}

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---
name: axiom-mapkit
description: Use when implementing maps, annotations, search, directions, or debugging MapKit display/performance issues - SwiftUI Map, MKMapView, MKLocalSearch, clustering, Look Around
license: MIT
metadata:
version: "1.0.0"
last-updated: "2026-02-26"
---
# MapKit Patterns
MapKit patterns and anti-patterns for iOS apps. Prevents common mistakes: using MKMapView when SwiftUI Map suffices, annotations in view bodies, setRegion loops, and performance issues with large annotation counts.
## When to Use
- Adding a map to your iOS app
- Displaying annotations, markers, or custom pins
- Implementing search (address, POI, autocomplete)
- Adding directions/routing to a map
- Debugging map display issues (annotations not showing, region jumping)
- Optimizing map performance with many annotations
- Deciding between SwiftUI Map and MKMapView
## Related Skills
- `axiom-mapkit-ref` — Complete API reference
- `axiom-mapkit-diag` — Symptom-based troubleshooting
- `axiom-core-location` — Location authorization and monitoring
---
## Part 1: Anti-Patterns (with Time Costs)
| Anti-Pattern | Time Cost | Fix |
|---|---|---|
| Using MKMapView when SwiftUI Map suffices | 2-4 hours UIViewRepresentable boilerplate | Use SwiftUI `Map {}` for standard map features (iOS 17+) |
| Creating annotations in SwiftUI view body | UI freeze with 100+ items, view recreation on every update | Move annotations to model, use `@State` or `@Observable` |
| No annotation view reuse (MKMapView) | Memory spikes, scroll lag with 500+ annotations | `dequeueReusableAnnotationView(withIdentifier:for:)` |
| `setRegion` in `updateUIView` without guard | Infinite loop — region change triggers update, update sets region | Guard with `mapView.region != region` or use flag |
| Ignoring MapCameraPosition (SwiftUI) | Can't programmatically control camera, broken "center on user" | Bind `position` parameter to `@State var cameraPosition` |
| Synchronous geocoding on main thread | UI freeze for 1-3 seconds per geocode | Use `CLGeocoder().geocodeAddressString` with async/await |
| Not filtering annotations to visible region | Loading all 10K annotations at once | Use `mapView.annotations(in:)` or fetch by visible region |
| Ignoring `resultTypes` in MKLocalSearch | Irrelevant results, slow search | Set `.resultTypes = [.pointOfInterest]` or `.address` to filter |
---
## Part 2: Decision Trees
### Decision Tree 1: SwiftUI Map vs MKMapView
```dot
digraph {
"Need map in app?" [shape=diamond];
"iOS 17+ target?" [shape=diamond];
"Need custom tile overlay?" [shape=diamond];
"Need fine-grained delegate control?" [shape=diamond];
"Use SwiftUI Map" [shape=box];
"Use MKMapView\nvia UIViewRepresentable" [shape=box];
"Need map in app?" -> "iOS 17+ target?" [label="yes"];
"iOS 17+ target?" -> "Need custom tile overlay?" [label="yes"];
"iOS 17+ target?" -> "Use MKMapView\nvia UIViewRepresentable" [label="no"];
"Need custom tile overlay?" -> "Use MKMapView\nvia UIViewRepresentable" [label="yes"];
"Need custom tile overlay?" -> "Need fine-grained delegate control?" [label="no"];
"Need fine-grained delegate control?" -> "Use MKMapView\nvia UIViewRepresentable" [label="yes"];
"Need fine-grained delegate control?" -> "Use SwiftUI Map" [label="no"];
}
```
#### When SwiftUI Map is Right (most apps)
- Standard map with markers and annotations
- Programmatic camera control
- Built-in user location display
- Shape overlays (circle, polygon, polyline)
- Map style selection (standard, imagery, hybrid)
- Selection handling
- Clustering
#### When MKMapView is Required
- Custom tile overlays (e.g., OpenStreetMap, custom imagery)
- Fine-grained delegate control (willBeginLoadingMap, didFinishLoadingMap)
- Custom annotation view animations beyond SwiftUI
- Pre-iOS 17 deployment target
- Advanced overlay rendering with custom MKOverlayRenderer subclasses
### Decision Tree 2: Annotation Strategy by Count
```
Annotation count?
├─ < 100 → Use Marker/Annotation directly in Map {} content builder
│ Simple, declarative, no performance concern
├─ 100-1000 → Enable clustering
│ Set .clusteringIdentifier on annotation views
│ SwiftUI: Marker("", coordinate:).tag(id)
│ MKMapView: view.clusteringIdentifier = "poi"
└─ 1000+ → Server-side clustering or visible-region filtering
Fetch only annotations within mapView.region
Or pre-cluster on server, send cluster centroids
MKMapView with view reuse is preferred for very large datasets
```
#### Visible-Region Filtering (SwiftUI)
Only load annotations within the visible map region. Prevents loading all 10K+ annotations at once:
```swift
struct MapView: View {
@State private var cameraPosition: MapCameraPosition = .automatic
@State private var visibleAnnotations: [Location] = []
let allLocations: [Location] // Full dataset
var body: some View {
Map(position: $cameraPosition) {
ForEach(visibleAnnotations) { location in
Marker(location.name, coordinate: location.coordinate)
}
}
.onMapCameraChange(frequency: .onEnd) { context in
visibleAnnotations = allLocations.filter { location in
context.region.contains(location.coordinate)
}
}
}
}
extension MKCoordinateRegion {
func contains(_ coordinate: CLLocationCoordinate2D) -> Bool {
let latRange = (center.latitude - span.latitudeDelta / 2)...(center.latitude + span.latitudeDelta / 2)
let lngRange = (center.longitude - span.longitudeDelta / 2)...(center.longitude + span.longitudeDelta / 2)
return latRange.contains(coordinate.latitude) && lngRange.contains(coordinate.longitude)
}
}
```
#### Why Clustering Matters
Without clustering at 500 annotations:
- Map is unreadable (pins overlap completely)
- Scroll/zoom lag increases with every annotation
- Memory grows linearly with annotation count
With clustering:
- User sees meaningful groups with counts
- Only visible cluster markers rendered
- Tap to expand reveals individual annotations
### Decision Tree 3: Search and Directions
```
Search implementation:
├─ User types search query
│ └─ MKLocalSearchCompleter (real-time autocomplete)
│ Configure: resultTypes, region bias
│ └─ User selects result
│ └─ MKLocalSearch (full result with MKMapItem)
│ Use completion.title for MKLocalSearch.Request
└─ Programmatic search (e.g., "nearest gas station")
└─ MKLocalSearch with naturalLanguageQuery
Configure: resultTypes, region, pointOfInterestFilter
Directions implementation:
├─ MKDirections.Request
│ Set source (MKMapItem.forCurrentLocation()) and destination
│ Set transportType (.automobile, .walking, .transit)
└─ MKDirections.calculate()
└─ MKRoute
├─ .polyline → Display as MapPolyline or MKPolylineRenderer
├─ .expectedTravelTime → Show ETA
├─ .distance → Show distance
└─ .steps → Turn-by-turn instructions
```
---
## Part 3: Pressure Scenarios
### Scenario 1: "Just Wrap MKMapView in UIViewRepresentable"
**Setup**: Adding a map to a SwiftUI app. Developer is familiar with MKMapView from UIKit projects.
**Pressure**: "I know MKMapView well. SwiftUI Map is new and might be limited."
**Expected with skill**: Check the decision tree. If the app needs standard markers, annotations, camera control, user location, and shape overlays — SwiftUI Map handles all of that. Use it.
**Anti-pattern without skill**: 200+ lines of UIViewRepresentable + Coordinator wrapping MKMapView, manually bridging state, implementing delegate methods for annotation views, fighting updateUIView infinite loops — when 20 lines of `Map {}` with content builder would have worked.
**Time cost**: 2-4 hours of unnecessary boilerplate + ongoing maintenance burden.
**The test**: Can you list a specific feature the app needs that SwiftUI Map cannot provide? If not, use SwiftUI Map.
### Scenario 2: "Add All 10,000 Pins to the Map"
**Setup**: App has a database of 10,000 location data points. Product manager wants users to see all locations on the map.
**Pressure**: "Users need to see ALL locations. Just add them all."
**Expected with skill**: Use clustering + visible region filtering. 10K annotations without clustering is unusable — pins overlap, scrolling lags, memory spikes. Clustering shows meaningful groups. Visible region filtering loads only what's on screen.
**Anti-pattern without skill**: Adding all 10,000 annotations at once. Map becomes an unreadable blob of overlapping pins. Scroll lag makes the app feel broken. Memory usage spikes 200-400MB.
**Implementation path**:
1. Enable clustering (`.clusteringIdentifier`)
2. Fetch annotations only within visible region (`.onMapCameraChange` + query)
3. Server-side pre-clustering for datasets > 5K if possible
### Scenario 3: "Search Isn't Finding Results"
**Setup**: MKLocalSearch returns irrelevant or empty results. Developer considers adding Google Maps SDK.
**Pressure**: "MapKit search is broken. Let me add a third-party SDK."
**Expected with skill**: Check configuration first. MapKit search needs:
1. `resultTypes` — filter to `.pointOfInterest` or `.address` (default returns everything)
2. `region` — bias results to the visible map region
3. Query format — natural language like "coffee shops" works; structured queries don't
**Anti-pattern without skill**: Adding Google Maps SDK (50+ MB binary, API key management, billing setup) when MapKit search works correctly with proper configuration.
**Time cost**: 4-8 hours adding third-party SDK vs 5 minutes configuring MapKit search.
---
## Part 4: Core Location Integration
MapKit and Core Location interact in ways that surprise developers.
### Implicit Authorization
When you set `showsUserLocation = true` on MKMapView or add `UserAnnotation()` in SwiftUI Map, MapKit implicitly requests location authorization if it hasn't been requested yet.
This means:
- The authorization prompt appears at map display time, not when the developer expects
- The user sees a prompt with no context about why location is needed
- If denied, the blue dot silently doesn't appear
#### Recommended Pattern
Request authorization explicitly BEFORE showing the map:
```swift
// 1. Request authorization with context
let session = CLServiceSession(authorization: .whenInUse)
// 2. Then show map with user location
Map {
UserAnnotation()
}
```
### CLServiceSession (iOS 17+)
For continuous location display on a map, create a `CLServiceSession`:
```swift
@Observable
class MapModel {
var cameraPosition: MapCameraPosition = .automatic
private var locationSession: CLServiceSession?
func startShowingUserLocation() {
locationSession = CLServiceSession(authorization: .whenInUse)
}
func stopShowingUserLocation() {
locationSession = nil
}
}
```
### Cross-Reference
For full authorization decision trees, monitoring patterns, and background location:
- `axiom-core-location` — Authorization strategy, monitoring approach
- `axiom-core-location-diag` — "Location not working" troubleshooting
- `axiom-energy` — Location as battery subsystem
---
## Part 5: SwiftUI Map Quick Start
The most common pattern — a map with markers and user location:
```swift
struct ContentView: View {
@State private var cameraPosition: MapCameraPosition = .automatic
@State private var selectedItem: MKMapItem?
let locations: [Location] // Your model
var body: some View {
Map(position: $cameraPosition, selection: $selectedItem) {
UserAnnotation()
ForEach(locations) { location in
Marker(location.name, coordinate: location.coordinate)
.tint(location.category.color)
}
}
.mapStyle(.standard(elevation: .realistic))
.mapControls {
MapUserLocationButton()
MapCompass()
MapScaleView()
}
.onChange(of: selectedItem) { _, item in
if let item {
handleSelection(item)
}
}
}
}
```
#### Key Points
- `@State var cameraPosition` — bind for programmatic camera control
- `selection: $selectedItem` — handle tap on markers
- `MapCameraPosition.automatic` — system manages initial view
- `.mapControls {}` — built-in UI for location button, compass, scale
- `ForEach` in content builder — dynamic annotations from data
---
## Part 6: Search Implementation Pattern
Complete search with autocomplete:
```swift
@Observable
class SearchModel {
var searchText = ""
var completions: [MKLocalSearchCompletion] = []
var searchResults: [MKMapItem] = []
private let completer = MKLocalSearchCompleter()
private var completerDelegate: CompleterDelegate?
init() {
completerDelegate = CompleterDelegate { [weak self] results in
self?.completions = results
}
completer.delegate = completerDelegate
completer.resultTypes = [.pointOfInterest, .address]
}
func updateSearch(_ text: String) {
searchText = text
completer.queryFragment = text
}
func search(for completion: MKLocalSearchCompletion) async throws {
let request = MKLocalSearch.Request(completion: completion)
request.resultTypes = [.pointOfInterest, .address]
let search = MKLocalSearch(request: request)
let response = try await search.start()
searchResults = response.mapItems
}
func search(query: String, in region: MKCoordinateRegion) async throws {
let request = MKLocalSearch.Request()
request.naturalLanguageQuery = query
request.region = region
request.resultTypes = .pointOfInterest
let search = MKLocalSearch(request: request)
let response = try await search.start()
searchResults = response.mapItems
}
}
```
#### MKLocalSearchCompleter Delegate (Required)
```swift
class CompleterDelegate: NSObject, MKLocalSearchCompleterDelegate {
let onUpdate: ([MKLocalSearchCompletion]) -> Void
init(onUpdate: @escaping ([MKLocalSearchCompletion]) -> Void) {
self.onUpdate = onUpdate
}
func completerDidUpdateResults(_ completer: MKLocalSearchCompleter) {
onUpdate(completer.results)
}
func completer(_ completer: MKLocalSearchCompleter, didFailWithError error: Error) {
// Handle error network issues, rate limiting
}
}
```
#### Rate Limiting
Apple rate-limits MapKit search. For autocomplete:
- `MKLocalSearchCompleter` handles its own throttling internally
- Don't create a new completer per keystroke — reuse one instance
- Set `queryFragment` on each keystroke; the completer debounces
For `MKLocalSearch`:
- Don't fire a search on every keystroke — use the completer for autocomplete
- Fire `MKLocalSearch` only when the user selects a completion or submits
---
## Part 7: Directions Implementation Pattern
```swift
func calculateDirections(
from source: CLLocationCoordinate2D,
to destination: MKMapItem,
transportType: MKDirectionsTransportType = .automobile
) async throws -> MKRoute {
let request = MKDirections.Request()
request.source = MKMapItem(placemark: MKPlacemark(coordinate: source))
request.destination = destination
request.transportType = transportType
let directions = MKDirections(request: request)
let response = try await directions.calculate()
guard let route = response.routes.first else {
throw MapError.noRouteFound
}
return route
}
```
#### Displaying the Route (SwiftUI)
```swift
Map(position: $cameraPosition) {
if let route {
MapPolyline(route.polyline)
.stroke(.blue, lineWidth: 5)
}
Marker("Start", coordinate: startCoord)
Marker("End", coordinate: endCoord)
}
```
#### Displaying the Route (MKMapView)
```swift
// Add overlay
mapView.addOverlay(route.polyline, level: .aboveRoads)
// Implement renderer delegate
func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
if let polyline = overlay as? MKPolyline {
let renderer = MKPolylineRenderer(polyline: polyline)
renderer.strokeColor = .systemBlue
renderer.lineWidth = 5
return renderer
}
return MKOverlayRenderer(overlay: overlay)
}
```
#### Route Information
```swift
let route: MKRoute = ...
let travelTime = route.expectedTravelTime // TimeInterval in seconds
let distance = route.distance // CLLocationDistance in meters
let steps = route.steps // [MKRoute.Step]
for step in steps {
print("\(step.instructions)\(step.distance)m")
// "Turn right on Main St 450m"
}
```
---
## Part 8: Clustering Pattern
### SwiftUI (iOS 17+)
```swift
Map(position: $cameraPosition) {
ForEach(locations) { location in
Marker(location.name, coordinate: location.coordinate)
.tag(location.id)
}
.mapItemClusteringIdentifier("locations")
}
```
### MKMapView
```swift
func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
if let cluster = annotation as? MKClusterAnnotation {
let view = mapView.dequeueReusableAnnotationView(
withIdentifier: "cluster",
for: annotation
) as! MKMarkerAnnotationView
view.markerTintColor = .systemBlue
view.glyphText = "\(cluster.memberAnnotations.count)"
return view
}
let view = mapView.dequeueReusableAnnotationView(
withIdentifier: "pin",
for: annotation
) as! MKMarkerAnnotationView
view.clusteringIdentifier = "locations"
view.markerTintColor = .systemRed
return view
}
```
#### Clustering Requirements
1. All annotation views that should cluster MUST share the same `clusteringIdentifier`
2. Register annotation view classes: `mapView.register(MKMarkerAnnotationView.self, forAnnotationViewWithReuseIdentifier: "pin")`
3. Clustering only activates when annotations physically overlap at the current zoom level
4. System manages cluster/uncluster animation automatically
---
## Part 9: Pre-Release Checklist
- [ ] Map loads and displays correctly
- [ ] Annotations appear at correct coordinates (lat/lng not swapped)
- [ ] Clustering works with 100+ annotations
- [ ] Search returns relevant results (resultTypes configured)
- [ ] Camera position controllable programmatically
- [ ] Memory stable when scrolling/zooming with many annotations
- [ ] User location shows correctly (authorization handled before display)
- [ ] Directions render as polyline overlay
- [ ] Map works in Dark Mode (map styles adapt automatically)
- [ ] Accessibility: VoiceOver announces map elements
- [ ] No setRegion/updateUIView infinite loops (if using MKMapView)
- [ ] MKLocalSearchCompleter reused (not recreated per keystroke)
- [ ] Annotation views reused via `dequeueReusableAnnotationView` (MKMapView)
- [ ] Look Around availability checked before displaying (`MKLookAroundSceneRequest`)
---
## Resources
**WWDC**: 2023-10043, 2024-10094
**Docs**: /mapkit, /mapkit/map
**Skills**: mapkit-ref, mapkit-diag, core-location

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interface:
display_name: "MapKit"
short_description: "Implementing maps, annotations, search, directions, or debugging MapKit display/performance issues"