iOS as Central - peripheral delegate

peripheral-delegate.swift

// Implement peripheral callback methods
extension SocialService: CBPeripheralDelegate {

    func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?) {
      // Discover characteristics
    }

    func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
      // Request for TraceCharacteristic value -- TraceToken
    }

    func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
      // Voila! Trace Token received  
      // Do amazing things with it
    }

}