Unrecognized selector -[MyClass centralManager:didUpdateMTUForPeripheral:]

I'm implementing an app to connect to a bluetooth printer using CoreBluetooth. Here is some part of my code.

  var centralManager: CBCentralManager?
  var printerPeripheral: CBPeripheral?
  var printerCharacteristic: CBCharacteristic?

  public init() {
    centralManager = CBCentralManager(delegate: self, queue: nil)
  }

  public func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) {
    if peripheral.name?.contains("printername") == true {
      printerPeripheral = peripheral
      centralManager?.connect(printerPeripheral!, options: nil)
    }
  }
  
  public func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral) {
    printerPeripheral?.delegate = self
    printerPeripheral?.discoverServices(nil)
  }

  public func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?) {
    for service in peripheral.services ?? [] {
      peripheral.discoverCharacteristics(nil, for: service)
    }
  }
  
  public func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {

  }

After the line printerPeripheral?.discoverServices(nil), I got the error. Unrecognized selector -[MyPrinterManager centralManager:didUpdateMTUForPeripheral:]

It has not yet reached didDiscoverServices nor didDiscoverCharacteristicsFor service

I can't find anything about didUpdateMTUForPeripheral anywhere. Anyone has any idea how I should fix this?