MapKit Camera (SwiftUI)

MapCameraBounds limits where the map camera can go, and MapCameraPosition is the two-way binding that reads and drives it. Together they keep the user inside your area and your code in control of the viewport.

Bounding the Map

Build a MapCameraBounds from an MKMapRect or MKCoordinateRegion. The user cannot pan outside it. The minimumDistance and maximumDistance parameters clamp zoom, in meters.

let rect = MKMapRect(
  origin: MKMapPoint(.newYork),
  size: MKMapSize(width: 1, height: 1)
)

Map(
  bounds: MapCameraBounds(
    centerCoordinateBounds: rect,
    minimumDistance: 10,
    maximumDistance: 100
  )
) {
  Marker("New York", monogram: Text("NY"), coordinate: .newYork)
}

MKMapRect measures in map points, a flat 2D projection; MKMapPoint converts between coordinates and map points. Use MKCoordinateRegion instead when you prefer latitude and longitude deltas.

A Rect That Fits All Markers

To bound the map around a set of coordinates, union one small rect per coordinate.

let coordinates: [CLLocationCoordinate2D] = [.newYork, .sanFrancisco, .seattle]
let rect = coordinates
  .map { MKMapRect(origin: .init($0), size: .init(width: 1, height: 1)) }
  .reduce(MKMapRect.null) { $0.union($1) }

Driving the Camera

MapCameraPosition builds from a camera, rect, region, item, or the user location. Setting the bound state moves the camera; the user dragging the map writes back into it.

@State private var position: MapCameraPosition = .camera(
  .init(centerCoordinate: .newYork, distance: 0)
)

Map(position: $position) { /* content */ }
  .onAppear {
    position = .camera(.init(centerCoordinate: .sanFrancisco, distance: 0))
  }

userLocation(followsHeading:fallback:) keeps the camera on the user, rotating with their heading, and falls back when location is unavailable.

Reading the Position Back

The position exposes optional camera, region, and rect values; each is non-nil only when that representation is in use. positionedByUser tells you whether the user moved the camera or your code did, which is the flag to check before recentering.

.onChange(of: position) {
  print(position.positionedByUser)
  print(position.camera as Any)
}