BLE Advertising

Hi, I am trying to write simple code that my iPhone acts as BLE peripheral (advertise packet). but i cannot see the advertisement on other devices that do scanning. What could be the cause?

Code snippet

============= import SwiftUI import CoreBluetooth

// 1. Conform to CBPeripheralManagerDelegate class BLEAdvertiser: NSObject, ObservableObject, CBPeripheralManagerDelegate { var peripheralManager: CBPeripheralManager?

// 2. Start advertising
func startAdvertising() {
    peripheralManager = CBPeripheralManager(delegate: self, queue: nil)
}

// 3. CBPeripheralManagerDelegate method called when state changes
func peripheralManagerDidUpdateState(_ peripheral: CBPeripheralManager) {
        switch peripheral.state {
        case .poweredOn:
            // Define a service UUID
            let serviceUUID = CBUUID(string: "1234") // Custom UUID for your service
            
            // Create a CBMutableService
            let service = CBMutableService(type: serviceUUID, primary: true)
            
            // Add service to the peripheral manager
            peripheralManager?.add(service)
            
            // Start advertising the service
            let advertisementData: [String: Any] = [
                CBAdvertisementDataServiceUUIDsKey: [serviceUUID],
                CBAdvertisementDataLocalNameKey: "My iPhone"
            ]
            peripheralManager?.startAdvertising(advertisementData)
            
            print("Started advertising!")
        case .poweredOff:
            print("Bluetooth is powered off.")
        case .resetting:
            print("Bluetooth is resetting.")
        case .unauthorized:
            print("Bluetooth access is unauthorized.")
        case .unsupported:
            print("Bluetooth is unsupported on this device.")
        case .unknown:
            print("Bluetooth state is unknown.")
        @unknown default:
            print("A new state that we don’t know about.")
        }
}

// 4. Optional: Handle peripheral manager adding service
func peripheralManager(_ peripheral: CBPeripheralManager, didAdd service: CBService, error: Error?) {
    if let error = error {
        print("Failed to add service: \(error.localizedDescription)")
        return
    }
    print("Service added successfully!")
}

}

struct ContentView: View { @StateObject private var bleAdvertiser = BLEAdvertiser()

var body: some View {
    VStack {
        Text("BLE Advertising")
            .font(.largeTitle)
            .padding()
        
        Button(action: {
            bleAdvertiser.startAdvertising()
        }) {
            Text("Start Advertising")
                .padding()
                .background(Color.blue)
                .foregroundColor(.white)
                .cornerRadius(10)
        }
    }
}

}