Brother Printer SDK call back function doesn't be triggered

I take a reference from official document:https://support.brother.com/g/s/es/htmldoc/mobilesdk/guide/discover-printer.html

I use pod to install the Brother Printer SDK

pod 'BRLMPrinterKit'

then I import h file from SDK

nihaod-Bridging-Header:

#import <React/RCTBridgeModule.h>#import <BRLMPrinterKit/BRLMPrinterKit.h>#import <BRLMPrinterKit/BRPtouchNetworkManager.h>#import <BRLMPrinterKit/BRPtouchDeviceInfo.h>#import <BRLMPrinterKit/BRPtouchPrinter.h>#import <BRLMPrinterKit/BRPtouchPrinterData.h>#import <BRLMPrinterKit/BRPtouchPrinterKit.h>#import <BRLMPrinterKit/BRPtouchPrintInfo.h>

LabelPrinter.swift:

import Foundation@objc(LabelPrinter)class LabelPrinter: NSObject, BRPtouchNetworkDelegate {  private var networkManager: BRPtouchNetworkManager?  @objc  func startSearchWiFiPrinter() {    print("startSearchWiFiPrinter")    let manager = BRPtouchNetworkManager()    manager.delegate = self    manager.startSearch(5)    self.networkManager = manager  }  // BRPtouchNetworkDelegate  func didFinishSearch(_ sender: Any!) {    print("start didFinishSearch")    guard let manager = sender as? BRPtouchNetworkManager else {        return    }    guard let devices = manager.getPrinterNetInfo() else {        return    }    for deviceInfo in devices {        if let deviceInfo = deviceInfo as? BRPtouchDeviceInfo {          print("Model: \(String(describing: deviceInfo.strModelName)), IP Address: \(String(describing: deviceInfo.strIPAddress))")        }    }  }}

When I call function startSearchWiFiPrinter, my log console just print startSearchWiFiPrinter, and then I thougt it will print start didFinishSearch after 5 seconds, but nothing happened.

Any one knows why function didFinishSearch doesn't be triggered ? Thanks.