What's New in SwiftData (iOS 27)

import SwiftData
import MapKit
import Observation

@Model
final class Trip {
    var name: String
    var destination: String
    var latitude: Double
    var longitude: Double
    var startDate: Date
    var endDate: Date

    init(name: String, destination: String, latitude: Double, longitude: Double, startDate: Date, endDate: Date) {
        self.name = name
        self.destination = destination
        self.latitude = latitude
        self.longitude = longitude
        self.startDate = startDate
        self.endDate = endDate
    }
}

@Observable
final class MapCameraController {
    var cameraBounds: MapCameraBounds = MapCameraBounds(centerCoordinateBounds: .world)

    private var observer: ResultsObserver<Trip>
    private var observationToken: ObservationTracking.Token?

    init(modelContainer: ModelContainer) {
        // ResultsObserver works like @Query but outside SwiftUI views
        observer = ResultsObserver<Trip>(
            modelContainer: modelContainer,
            sortBy: [SortDescriptor(\.startDate)]
        )

        // withContinuousObservation + .didSet fires after each change settles
        observationToken = withContinuousObservation(options: .didSet) { [weak self] in
            guard let self else { return }
            // Accessing results registers the dependency with Swift Observation
            _ = self.observer.results
            self.recalculateBounds()
        }
    }

    private func recalculateBounds() {
        let trips = observer.results
        guard !trips.isEmpty else {
            cameraBounds = MapCameraBounds(centerCoordinateBounds: .world)
            return
        }
        let coords = trips.map {
            CLLocationCoordinate2D(latitude: $0.latitude, longitude: $0.longitude)
        }
        let region = MKCoordinateRegion(coordinates: coords)
        cameraBounds = MapCameraBounds(centerCoordinateBounds: region)
    }
}

// MARK: - SwiftUI integration
import SwiftUI

struct TripMapView: View {
    @State private var controller: MapCameraController

    init(modelContainer: ModelContainer) {
        _controller = State(initialValue: MapCameraController(modelContainer: modelContainer))
    }

    var body: some View {
        Map(bounds: controller.cameraBounds)
    }
}