Add native iOS beacon scanner with CoreBluetooth

- BeaconScanner.swift: Native scanner using CBCentralManager
- AppDelegate.swift: Wire up MethodChannel (same API as Android)
- beacon_channel.dart: Support iOS in isSupported check
- beacon_scanner_service.dart: Use native scanner on both platforms

iOS now gets the same fast 2-second scan as Android.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ios/Runner/AppDelegate.swift

@@ -3,11 +3,60 @@ import UIKit
 
 @main
 @objc class AppDelegate: FlutterAppDelegate {
-  override func application(
-    _ application: UIApplication,
-    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
-  ) -> Bool {
-    GeneratedPluginRegistrant.register(with: self)
-    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
-  }
+
+    private let channelName = "com.payfrit.app/beacon"
+    private var beaconScanner: BeaconScanner?
+
+    override func application(
+        _ application: UIApplication,
+        didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
+    ) -> Bool {
+        GeneratedPluginRegistrant.register(with: self)
+
+        // Set up beacon scanner method channel
+        guard let controller = window?.rootViewController as? FlutterViewController else {
+            return super.application(application, didFinishLaunchingWithOptions: launchOptions)
+        }
+
+        beaconScanner = BeaconScanner()
+
+        let channel = FlutterMethodChannel(name: channelName, binaryMessenger: controller.binaryMessenger)
+
+        channel.setMethodCallHandler { [weak self] (call: FlutterMethodCall, result: @escaping FlutterResult) in
+            guard let self = self, let scanner = self.beaconScanner else {
+                result(FlutterError(code: "UNAVAILABLE", message: "Beacon scanner not initialized", details: nil))
+                return
+            }
+
+            switch call.method {
+            case "hasPermissions":
+                result(scanner.hasPermissions())
+
+            case "isBluetoothEnabled":
+                result(scanner.isBluetoothEnabled())
+
+            case "startScan":
+                var regions: [String] = []
+                if let args = call.arguments as? [String: Any],
+                   let regionList = args["regions"] as? [String] {
+                    regions = regionList
+                }
+
+                scanner.startScan(regions: regions) { beacons in
+                    result(beacons)
+                } onError: { error in
+                    result(FlutterError(code: "SCAN_ERROR", message: error, details: nil))
+                }
+
+            case "stopScan":
+                scanner.stopScan()
+                result(nil)
+
+            default:
+                result(FlutterMethodNotImplemented)
+            }
+        }
+
+        return super.application(application, didFinishLaunchingWithOptions: launchOptions)
+    }
 }

ios/Runner/BeaconScanner.swift

@@ -0,0 +1,234 @@
+import Foundation
+import CoreBluetooth
+import CoreLocation
+
+/// Native beacon scanner using CoreBluetooth.
+/// Scans for iBeacon advertisements and returns UUID + RSSI.
+class BeaconScanner: NSObject {
+
+    private static let TAG = "BeaconScanner"
+
+    // iBeacon manufacturer ID (Apple)
+    private static let IBEACON_MANUFACTURER_ID: UInt16 = 0x004C
+
+    // Scan duration in seconds
+    private static let SCAN_DURATION: TimeInterval = 2.0
+
+    // Minimum RSSI threshold
+    private static let MIN_RSSI: Int = -90
+
+    private var centralManager: CBCentralManager?
+    private var locationManager: CLLocationManager?
+    private var isScanning = false
+
+    // Callbacks
+    private var onComplete: (([[String: Any]]) -> Void)?
+    private var onError: ((String) -> Void)?
+
+    // Collected beacon data: UUID -> list of RSSI samples
+    private var beaconSamples: [String: [Int]] = [:]
+
+    // Timer for scan completion
+    private var scanTimer: Timer?
+
+    // Bluetooth state
+    private var bluetoothState: CBManagerState = .unknown
+    private var pendingScan = false
+    private var pendingRegions: [String]?
+
+    override init() {
+        super.init()
+        centralManager = CBCentralManager(delegate: self, queue: nil, options: [
+            CBCentralManagerOptionShowPowerAlertKey: false
+        ])
+        locationManager = CLLocationManager()
+    }
+
+    /// Check if Bluetooth permissions are granted
+    func hasPermissions() -> Bool {
+        // Check Bluetooth authorization
+        if #available(iOS 13.1, *) {
+            let bluetoothAuth = CBCentralManager.authorization
+            if bluetoothAuth != .allowedAlways {
+                return false
+            }
+        }
+
+        // Check location authorization (required for beacon scanning)
+        let locationAuth = locationManager?.authorizationStatus ?? .notDetermined
+        return locationAuth == .authorizedWhenInUse || locationAuth == .authorizedAlways
+    }
+
+    /// Check if Bluetooth is enabled
+    func isBluetoothEnabled() -> Bool {
+        return bluetoothState == .poweredOn
+    }
+
+    /// Start scanning for beacons
+    func startScan(regions: [String], onComplete: @escaping ([[String: Any]]) -> Void, onError: @escaping (String) -> Void) {
+        if isScanning {
+            onError("Scan already in progress")
+            return
+        }
+
+        if !hasPermissions() {
+            onError("Bluetooth or location permissions not granted")
+            return
+        }
+
+        // If Bluetooth isn't ready yet, queue the scan
+        if bluetoothState != .poweredOn {
+            if bluetoothState == .poweredOff {
+                onError("Bluetooth is not enabled")
+                return
+            }
+            // State might be unknown/resetting, wait for it
+            pendingScan = true
+            pendingRegions = regions
+            self.onComplete = onComplete
+            self.onError = onError
+            return
+        }
+
+        performScan(regions: regions, onComplete: onComplete, onError: onError)
+    }
+
+    private func performScan(regions: [String], onComplete: @escaping ([[String: Any]]) -> Void, onError: @escaping (String) -> Void) {
+        NSLog("\(BeaconScanner.TAG): Starting CoreBluetooth beacon scan")
+
+        isScanning = true
+        self.onComplete = onComplete
+        self.onError = onError
+        beaconSamples.removeAll()
+
+        // Start scanning for all devices (we'll filter for iBeacons in didDiscover)
+        // Note: CoreBluetooth doesn't allow filtering by manufacturer data directly
+        centralManager?.scanForPeripherals(withServices: nil, options: [
+            CBCentralManagerScanOptionAllowDuplicatesKey: true
+        ])
+
+        // Schedule scan completion
+        scanTimer = Timer.scheduledTimer(withTimeInterval: BeaconScanner.SCAN_DURATION, repeats: false) { [weak self] _ in
+            self?.completeScan()
+        }
+    }
+
+    /// Stop scanning
+    func stopScan() {
+        NSLog("\(BeaconScanner.TAG): Stopping beacon scan")
+
+        scanTimer?.invalidate()
+        scanTimer = nil
+        isScanning = false
+        pendingScan = false
+
+        centralManager?.stopScan()
+    }
+
+    private func completeScan() {
+        NSLog("\(BeaconScanner.TAG): Scan complete. Found \(beaconSamples.count) unique beacons")
+
+        centralManager?.stopScan()
+        isScanning = false
+
+        // Build results
+        var results: [[String: Any]] = []
+        for (uuid, samples) in beaconSamples {
+            let avgRssi = samples.reduce(0, +) / max(samples.count, 1)
+            results.append([
+                "uuid": uuid,
+                "rssi": avgRssi,
+                "samples": samples.count
+            ])
+        }
+
+        // Sort by RSSI descending (strongest first)
+        results.sort { ($0["rssi"] as? Int ?? -100) > ($1["rssi"] as? Int ?? -100) }
+
+        onComplete?(results)
+        onComplete = nil
+        onError = nil
+    }
+
+    /// Parse iBeacon UUID from manufacturer data
+    private func parseIBeaconUuid(from advertisementData: [String: Any]) -> (uuid: String, rssi: Int)? {
+        guard let manufacturerData = advertisementData[CBAdvertisementDataManufacturerDataKey] as? Data else {
+            return nil
+        }
+
+        // iBeacon format:
+        // Bytes 0-1: Company ID (0x004C for Apple)
+        // Byte 2: Type (0x02)
+        // Byte 3: Length (0x15 = 21)
+        // Bytes 4-19: UUID (16 bytes)
+        // Bytes 20-21: Major
+        // Bytes 22-23: Minor
+        // Byte 24: TX Power
+
+        guard manufacturerData.count >= 25 else {
+            return nil
+        }
+
+        // Check Apple company ID (little endian)
+        let companyId = UInt16(manufacturerData[0]) | (UInt16(manufacturerData[1]) << 8)
+        guard companyId == BeaconScanner.IBEACON_MANUFACTURER_ID else {
+            return nil
+        }
+
+        // Check iBeacon type
+        guard manufacturerData[2] == 0x02 && manufacturerData[3] == 0x15 else {
+            return nil
+        }
+
+        // Extract UUID (bytes 4-19)
+        let uuidBytes = manufacturerData.subdata(in: 4..<20)
+        let uuid = uuidBytes.map { String(format: "%02X", $0) }.joined()
+
+        return (uuid: uuid, rssi: 0) // RSSI comes from the peripheral callback
+    }
+}
+
+// MARK: - CBCentralManagerDelegate
+extension BeaconScanner: CBCentralManagerDelegate {
+
+    func centralManagerDidUpdateState(_ central: CBCentralManager) {
+        bluetoothState = central.state
+        NSLog("\(BeaconScanner.TAG): Bluetooth state changed to \(central.state.rawValue)")
+
+        // If we had a pending scan and Bluetooth is now ready, start it
+        if pendingScan && central.state == .poweredOn {
+            pendingScan = false
+            if let regions = pendingRegions, let onComplete = onComplete, let onError = onError {
+                performScan(regions: regions, onComplete: onComplete, onError: onError)
+            }
+            pendingRegions = nil
+        } else if pendingScan && central.state == .poweredOff {
+            pendingScan = false
+            onError?("Bluetooth is not enabled")
+            onError = nil
+            onComplete = nil
+        }
+    }
+
+    func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String: Any], rssi RSSI: NSNumber) {
+        let rssiValue = RSSI.intValue
+
+        // Filter weak signals
+        guard rssiValue >= BeaconScanner.MIN_RSSI else {
+            return
+        }
+
+        // Try to parse as iBeacon
+        guard let beacon = parseIBeaconUuid(from: advertisementData) else {
+            return
+        }
+
+        NSLog("\(BeaconScanner.TAG): Detected iBeacon: \(beacon.uuid) RSSI=\(rssiValue)")
+
+        // Add sample
+        if beaconSamples[beacon.uuid] == nil {
+            beaconSamples[beacon.uuid] = []
+        }
+        beaconSamples[beacon.uuid]?.append(rssiValue)
+    }
+}

lib/services/beacon_channel.dart

@@ -26,12 +26,12 @@ class DetectedBeacon {
 }
 
 /// Native beacon scanner via MethodChannel
-/// Only works on Android. iOS falls back to Flutter plugin.
+/// Works on both Android and iOS using platform-specific implementations.
 class BeaconChannel {
   static const _channel = MethodChannel("com.payfrit.app/beacon");
 
-  /// Check if running on Android (native scanner only works there)
-  static bool get isSupported => Platform.isAndroid;
+  /// Check if native scanner is supported on this platform
+  static bool get isSupported => Platform.isAndroid || Platform.isIOS;
 
   /// Check if Bluetooth permissions are granted
   static Future<bool> hasPermissions() async {

lib/services/beacon_scanner_service.dart

@@ -90,17 +90,17 @@ class BeaconScannerService {
         return const BeaconScanResult(error: "No beacons configured");
       }
 
-      // Use native scanner on Android, Flutter plugin on iOS
+      // Use native scanner on both Android and iOS
       List<DetectedBeacon> detectedBeacons = [];
 
-      if (Platform.isAndroid) {
-        debugPrint('[BeaconScanner] Using native Android scanner...');
+      if (BeaconChannel.isSupported) {
+        debugPrint('[BeaconScanner] Using native scanner...');
         detectedBeacons = await BeaconChannel.startScan(
           regions: knownBeacons.keys.toList(),
         );
       } else {
-        // iOS: use Flutter plugin
-        debugPrint('[BeaconScanner] Using Flutter plugin for iOS...');
+        // Fallback: use Flutter plugin
+        debugPrint('[BeaconScanner] Using Flutter plugin fallback...');
         detectedBeacons = await _scanWithFlutterPlugin(knownBeacons);
       }