Bluetooth Test w/ESP and iOS - Advertising/filtering on service problem

Projects Programming
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I am trying to list only bluetooth devices in iOS with a certain service, but it is not showing up. I am using a HiLetgo ESP-WROOM-32 ESP32 ESP-32S Development Board and Arduino. The Arduino code is BLE_notify under ESP32 BLE Arduino in the ESP32 Dev Module of the examples. It defines a service:

#define SERVICE_UUID        "4fafc201-1fb5-459e-8fcc-c5c9c331914b"

...create it:

  // Create the BLE Service
  BLEService *pService = pServer->createService(SERVICE_UUID);

...and advertises it:

  // Start advertising
  BLEAdvertising *pAdvertising = BLEDevice::getAdvertising();
  pAdvertising->addServiceUUID(SERVICE_UUID);
  pAdvertising->setScanResponse(false);
  pAdvertising->setMinPreferred(0x0);  // set value to 0x00 to not advertise this parameter
  BLEDevice::startAdvertising();
  Serial.println("Waiting a client connection to notify...");

The Swift iOS code also defines the service:

let serviceCBUUID = CBUUID(string: "4fafc201-1fb5-459e-8fcc-c5c9c331914b")

...and I scan for the service:

self.centralManager?.scanForPeripherals(withServices: [serviceCBUUID])

but it does not appear. When I put nil for the withServices. It picks it up. I print the services:

func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) {
    
    if !peripherals.contains(peripheral) {
        var pname: String = peripheral.name ?? "unnamed device"
        if (pname.contains("Test Device")) {
            print("Peripheral name: \(peripheral.name)")
            print("Peripheral Discovered: \(peripheral)")
            print ("Advertisement Data : \(advertisementData)")
            print ("Services : \(peripheral.services)")
        }
        self.peripherals.append(peripheral)
        self.peripheralNames.append((peripheral.name ?? "unnamed device") + " [\(peripheral.identifier)]")
    }
}

...and services is nil:

Peripheral name: Optional("Test Device")
Peripheral Discovered: <CBPeripheral: 0x283019ad0, identifier = C7D8059E-42EE-A549-9AF9-C2DC93FBD712, name = Test Device, mtu = 0, state = disconnected>
Advertisement Data : ["kCBAdvDataRxSecondaryPHY": 0, "kCBAdvDataRxPrimaryPHY": 129, "kCBAdvDataTxPowerLevel": 3, "kCBAdvDataIsConnectable": 1, "kCBAdvDataTimestamp": 694870916.362642, "kCBAdvDataLocalName": Test Device]
Services : nil

I can connect to the peripheral and get the service.

func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?) {
    
    print("didDiscoverServices")
    guard let services = peripheral.services else {
        return
    }
    print("services count: \(services.count)")
    for service in services {
        print("service: \(service.description)")
    }
    
    discoverCharacteristics(peripheral: peripheral)
}

and I see the value:

service: <CBService: 0x281378340, isPrimary = YES, UUID = 4FAFC201-1FB5-459E-8FCC-C5C9C331914B>

I assume the problem is in the Arduino end because CoreBluetooth is identifying the services as nil, but I'm not really sure. Has anybody gotten this to work?

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