How to Build a Cycling Tracker App in SwiftUI

import SwiftData
import CoreLocation

@Model
final class CyclingRide {
    var id: UUID = UUID()
    var startDate: Date = Date.now
    var endDate: Date?
    var distanceMeters: Double = 0
    var durationSeconds: Double = 0
    var elevationGainMeters: Double = 0
    var averageSpeedKph: Double = 0
    var maxSpeedKph: Double = 0
    var title: String = ""
    @Relationship(deleteRule: .cascade)
    var routePoints: [RoutePoint] = []
}

@Model
final class RoutePoint {
    var latitude: Double = 0
    var longitude: Double = 0
    var altitude: Double = 0
    var timestamp: Date = Date.now

    var coordinate: CLLocationCoordinate2D {
        CLLocationCoordinate2D(latitude: latitude, longitude: longitude)
    }
}

struct DashboardView: View {
    @Query(sort: \CyclingRide.startDate, order: .reverse)
    private var rides: [CyclingRide]
    @State private var showingActiveRide = false

    var body: some View {
        NavigationStack {
            List {
                if !rides.isEmpty {
                    Section("Recent Rides") {
                        ForEach(rides) { ride in
                            NavigationLink(value: ride) {
                                RideRowView(ride: ride)
                            }
                        }
                    }
                }
            }
            .navigationTitle("Cycling")
            .navigationDestination(for: CyclingRide.self) { ride in
                RideDetailView(ride: ride)
            }
            .toolbar {
                ToolbarItem(placement: .primaryAction) {
                    Button("Start Ride", systemImage: "bicycle") {
                        showingActiveRide = true
                    }
                }
            }
            .fullScreenCover(isPresented: $showingActiveRide) {
                ActiveRideView()
            }
        }
    }
}

@Observable
final class LocationManager: NSObject, CLLocationManagerDelegate {
    private let manager = CLLocationManager()
    var routePoints: [CLLocation] = []
    var isTracking = false
    var currentSpeedKph: Double = 0
    var distanceKm: Double = 0

    override init() {
        super.init()
        manager.delegate = self
        manager.desiredAccuracy = kCLLocationAccuracyBestForNavigation
        manager.allowsBackgroundLocationUpdates = true
        manager.pausesLocationUpdatesAutomatically = false
    }

    func startTracking() {
        routePoints = []; distanceKm = 0; isTracking = true
        manager.startUpdatingLocation()
    }

    func stopTracking() { isTracking = false; manager.stopUpdatingLocation() }

    func locationManager(_ manager: CLLocationManager,
                         didUpdateLocations locations: [CLLocation]) {
        guard isTracking, let loc = locations.last,
              loc.horizontalAccuracy < 20 else { return }
        if let prev = routePoints.last {
            distanceKm += loc.distance(from: prev) / 1000
        }
        currentSpeedKph = max(0, loc.speed) * 3.6
        routePoints.append(loc)
    }
}

// LocationManager+Permissions.swift
// Upgrades authorization from "When In Use" to "Always"
// so background location tracking stays active with screen locked.

extension LocationManager {
    func requestPermissions() {
        switch manager.authorizationStatus {
        case .notDetermined:
            manager.requestWhenInUseAuthorization()
        case .authorizedWhenInUse:
            manager.requestAlwaysAuthorization()
        case .authorizedAlways:
            manager.allowsBackgroundLocationUpdates = true
        default:
            break  // Surface a Settings deep-link in the UI
        }
    }

    func locationManagerDidChangeAuthorization(_ manager: CLLocationManager) {
        if manager.authorizationStatus == .authorizedAlways {
            manager.allowsBackgroundLocationUpdates = true
        }
    }
}

// PrivacyInfo.xcprivacy: File ▶ New ▶ App Privacy
//   NSPrivacyAccessedAPICategoryLocation  →  reason CA92.1
// Info.plist: UIBackgroundModes → ["location"]
// Capabilities tab: Background Modes ▶ Location updates ✓