// In App Clip target Build Settings → Active Compilation Conditions: APPCLIP

#if !APPCLIP
// Full-app-only code (e.g., background tasks, App Intents)
#else
// App Clip specific code
#endif

@main
struct DonutShopClip: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
                .onContinueUserActivity(
                    NSUserActivityTypeBrowsingWeb
                ) { activity in
                    handleInvocation(activity)
                }
        }
    }

    private func handleInvocation(_ activity: NSUserActivity) {
        guard let url = activity.webpageURL,
              let components = URLComponents(url: url, resolvingAgainstBaseURL: true)
        else { return }

        // Extract path/query to determine context
        let locationID = components.queryItems?
            .first(where: { $0.name == "location" })?.value

        // Update UI for this location
    }
}

appclips:example.com

<meta name="apple-itunes-app"
      content="app-id=YOUR_APP_ID, app-clip-bundle-id=com.example.MyApp.Clip,
               app-clip-display=card">

// In both targets: add App Groups capability with the same group ID

// App Clip — write data
func saveOrderHistory(_ orders: [Order]) throws {
    guard let containerURL = FileManager.default.containerURL(
        forSecurityApplicationGroupIdentifier: "group.com.example.myapp.shared"
    ) else { return }

    let data = try JSONEncoder().encode(orders)
    let fileURL = containerURL.appendingPathComponent("orders.json")
    try data.write(to: fileURL)
}

// Full app — read migrated data
func loadMigratedOrders() throws -> [Order] {
    guard let containerURL = FileManager.default.containerURL(
        forSecurityApplicationGroupIdentifier: "group.com.example.myapp.shared"
    ) else { return [] }

    let fileURL = containerURL.appendingPathComponent("orders.json")
    guard FileManager.default.fileExists(atPath: fileURL.path) else { return [] }
    let data = try Data(contentsOf: fileURL)
    return try JSONDecoder().decode([Order].self, from: data)
}

// Write (App Clip)
let shared = UserDefaults(suiteName: "group.com.example.myapp.shared")
shared?.set(userToken, forKey: "authToken")

// Read (Full app)
let shared = UserDefaults(suiteName: "group.com.example.myapp.shared")
let token = shared?.string(forKey: "authToken")

struct OrderCompleteView: View {
    @State private var showOverlay = false

    var body: some View {
        VStack {
            Text("Order placed!")
            Button("Get the full app") { showOverlay = true }
        }
        .appStoreOverlay(isPresented: $showOverlay) {
            SKOverlay.AppClipConfiguration(position: .bottom)
        }
    }
}

func displayOverlay() {
    guard let scene = view.window?.windowScene else { return }

    let config = SKOverlay.AppClipConfiguration(position: .bottom)
    let overlay = SKOverlay(configuration: config)
    overlay.delegate = self
    overlay.present(in: scene)
}

import AppClip
import CoreLocation

func verifyLocation(from activity: NSUserActivity) {
    guard let payload = activity.appClipActivationPayload,
          let url = activity.webpageURL
    else { return }

    // Build the expected region (up to 500m radius)
    let center = CLLocationCoordinate2D(latitude: 37.334722, longitude: -122.008889)
    let region = CLCircularRegion(center: center, radius: 100, identifier: "store-42")

    payload.confirmAcquired(in: region) { inRegion, error in
        if let error = error as? APActivationPayloadError {
            switch error.code {
            case .doesNotMatch:
                // URL doesn't match registered App Clip URL
                break
            case .disallowed:
                // User denied location, or invocation wasn't NFC/visual code
                break
            @unknown default:
                break
            }
            return
        }

        if inRegion {
            // Confirmed — user is at the expected location
        } else {
            // User is not at expected location (e.g., NFC tag was moved)
        }
    }
}

<key>NSAppClip</key>
<dict>
    <key>NSAppClipRequestLocationConfirmation</key>
    <true/>
</dict>

// ❌ DON'T: Include large frameworks or bundled assets
// Importing heavyweight frameworks like RealityKit or large ML models
// pushes the App Clip well over 10–15 MB.

// ✅ DO: Use Asset Catalog thinning, exclude unused architectures,
// strip debug symbols, and split shared code into lean Swift packages.
// Measure with App Thinning Size Report after every change.

// ❌ DON'T: Only test App Clip with a direct Xcode launch
// This skips invocation URL handling and misses bugs.

// ✅ DO: Use the _XCAppClipURL environment variable in the scheme,
// or register a Local Experience in Settings → Developer → Local Experiences
// to test with realistic invocation URLs and App Clip cards.

// ❌ DON'T: Assume only the App Clip receives invocations
// When the user installs the full app, ALL invocations go to it.

// ✅ DO: Share invocation-handling code between both targets.
// The full app must handle every invocation URL the App Clip supports.
#if !APPCLIP
// Full app can additionally show richer features for the same URL
#endif

// ❌ DON'T: Store important data in the App Clip's sandboxed container
let fileURL = documentsDirectory.appendingPathComponent("userData.json")
// This data is DELETED when the system removes the App Clip.

// ✅ DO: Write to the shared App Group container or sync to a server
guard let shared = FileManager.default.containerURL(
    forSecurityApplicationGroupIdentifier: "group.com.example.shared"
) else { return }
let fileURL = shared.appendingPathComponent("userData.json")

// ❌ DON'T: Configure App Clip experiences in App Store Connect
// without setting up associated domains and the AASA file.
// Invocations from your website and advanced experiences will fail.

// ✅ DO: Add the Associated Domains entitlement with:
//   appclips:example.com
// AND host /.well-known/apple-app-site-association on your server:
// {
//   "appclips": {
//     "apps": ["TEAMID.com.example.MyApp.Clip"]
//   }
// }