Network+cellularTech.swift

import CoreTelephony

func getNetworkType() throws -> String {
  let networkInfo = CTTelephonyNetworkInfo()

  guard let accessTechnology = networkInfo.currentRadioAccessTechnology else {
    throw ReachabilityError.cannotGetCurrentRadioAccessTechnology
  }

  return networkStringToReadableString(accessTechnology)
}

func networkStringToReadableString(_ networkString: String) -> String {
  switch networkString {
    case CTRadioAccessTechnologyGPRS,
         CTRadioAccessTechnologyEdge,
         CTRadioAccessTechnologyCDMA1x:
      return "2G"
    case CTRadioAccessTechnologyWCDMA, 
         CTRadioAccessTechnologyHSDPA,
         CTRadioAccessTechnologyHSUPA,
         CTRadioAccessTechnologyCDMAEVDORev0,
         CTRadioAccessTechnologyCDMAEVDORevA,
         CTRadioAccessTechnologyCDMAEVDORevB,
         CTRadioAccessTechnologyeHRPD:
      return "3G"
    case CTRadioAccessTechnologyLTE:
        return "4G"
    default:
        return networkString
    }
  }
}