didDiscoverServices is not being called after a BLE connection

Question

I'm working with a BLE device which I need to verify. The BLE code I'm using is below

//Pragma Bluetooth Methods
func centralManagerDidUpdateState(_ central: CBCentralManager) {
    if central.state == .poweredOn {
        central.scanForPeripherals(withServices: nil, options: nil)
    } else {
        print("Bluetooth not available.")
    }
}

func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber){
    if let peripheralName = advertisementData[CBAdvertisementDataLocalNameKey] as? String {
        if peripheralName == "test-device1" {
            self.manager.stopScan()

            self.peripheral = peripheral
            self.peripheral.delegate = self

            self.manager.connect(peripheral, options: nil)
        }
    }

}

func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral) {
    peripheral.discoverServices(nil)
}

private func peripheral(peripheral: CBPeripheral, didDiscoverServices error: Error?) {
    for service in peripheral.services! {
        let thisService = service as CBService

        if service.uuid == SERVICE_UUID {
            peripheral.discoverCharacteristics(
                nil,
                for: thisService
            )
        }
    }
}

The process follows the anticipated route by passing through didDiscover and verifying the name as 'test-device1'. However, although it goes through the didConnect method and runs peripheral.discoverServices(nil) it never reaches the didDiscoverServices method. I've stepped through it several times and it always stops at didConnect().

What am I missing?

Answer 1

Method from the doc:

func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?)

Yours:

func peripheral(peripheral: CBPeripheral, didDiscoverServices error: Error?)

Erase it and rewrite it letting XCode autocompletion helps you, copy/paste it from the doc, or just add a _ that is missing.

The method is optional, internally CoreBluetooth framework check if the delegates responds to the selector (respondsToSelector()) and the selector includes that "_" which yours doesn't have. So it won't match and it won't call it because it's not the same.