didDiscover peripheral not called

Question

I want to use the CBCentralManager in order to find the bluetooth low energy peripherals around me. The centralManager is getting initiated, it starts correctly and it is scanning. But the didDiscover function is never called. I read all the other posts to this and similar problem and am 99% sure that my problem has not the same cause. Still, I cannot find what I did wrong.

import Foundation
import CoreBluetooth

@objc(SmallerBeaconServiceImpl)
class SmallerBeaconServiceImpl : NSObject, CBCentralManagerDelegate, CBPeripheralDelegate {

    private let centralManager : CBCentralManager

    func centralManagerDidUpdateState(_ central: CBCentralManager) {
        if central.state == CBManagerState.poweredOn && isRunning {
            startScanningForPeripherals()
        }
        print("updated state: \(central.state)")
    }

    func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) {
        print(peripheral.name ?? "no name")
    }

    func startScanningForPeripherals() {
        if centralManager.state != CBManagerState.poweredOn {
            return
        }

        centralManager.scanForPeripherals(withServices: nil, options: nil)
        print("is scanning: \(centralManager.isScanning)")
    }


    private(set) var isRunning = false

    func startListening() {
        if isRunning {
            return
        }

        isRunning = true

        print("started.")
        startScanningForPeripherals()
    }

    func stopListening() {
        if !isRunning {
            return
        }
        isRunning = false

        centralManager.stopScan()
    }

    override init() {
        centralManager = CBCentralManager()
        super.init()

        print("initiated")
    }
}

Answer 1

optional func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) is a CBCentralManagerDelegate method.

Your class SmallerBeaconServiceImpl is compliant with CBCentralManagerDelegate, but you didn't set your centralManager delegate (CBCentralManagerDelegate) property. That's why centralManager(_central:didDiscover:advertisementData:rssi) is not called.

This can be fixed with:

centralManager = CBCentralManager(delegate: self, queue: nil)