Not sure if arduino code is properly sending information over BLE characteristic

[sh0ppingemail]

can someoen please help me understand if i am sending data over my BLE charactersitics properly? for context, i am using core bluetooth on the ios side and i am finding that it is not being updated thatifnromation is being sent from the arduino. please help

#include <ArduinoBLE.h>

const char* deviceServiceUuid = "19b10000-e8f2-537e-4f6c-d104768a1214";
const char* deviceServiceCharacteristicUuid = "19b10001-e8f2-537e-4f6c-d104768a1214";
const char* uuid2 = "19b10002-e8f2-537e-4f6c-d104768a1214";

BLEService gestureService(deviceServiceUuid);
BLECharacteristic gestureCharacteristic(deviceServiceCharacteristicUuid, BLERead | BLEWrite, 20);
BLECharacteristic hello(uuid2, BLERead | BLEWrite, 20);

unsigned long previousMillis = 0;
const long interval = 10000; // interval in milliseconds (10 seconds)

void setup() {
  Serial.begin(9600);
  while (!Serial);

  if (!BLE.begin()) {
    Serial.println("starting BLE failed!");
    while (1);
  }
  BLE.setLocalName("VolumeSensor");

  BLE.setAdvertisedService(gestureService);
  gestureService.addCharacteristic(gestureCharacteristic);
  gestureService.addCharacteristic(hello);
  BLE.addService(gestureService);

  hello.setEventHandler(BLEWrite, helloCharacteristicRead);

  BLE.advertise();

  Serial.println("BLE peripheral device started, waiting for connections...");
}

void helloCharacteristicRead(BLEDevice central, BLECharacteristic characteristic) {
  hello.writeValue("Hello from hello characteristic!");
}

void loop() {
  BLEDevice central = BLE.central();

  if (central) {
    Serial.print("Connected to central: ");
    Serial.println(central.address());

    while (central.connected()) {
      unsigned long currentMillis = millis();
      if (currentMillis - previousMillis >= interval) {
        previousMillis = currentMillis;

        String volume = "10"; // Example volume value
        gestureCharacteristic.writeValue("volume");
        gestureCharacteristic.writeValue("String from gesture characteristic!");

        hello.writeValue("");

        Serial.print("Volume: ");
        Serial.println(volume);

        delay(10);
      }
    }

    Serial.print(F("Disconnected from central: "));
    Serial.println(central.address());
  }
}