This code crashes unless CFBridgingRetain is called. Any Ideas why?

gistfile1.txt

 private class func createReachabilityManager() -> AFNetworkReachabilityManager? {
       var localWifiAddress = sockaddr_in()
       bzero(&localWifiAddress, MemoryLayout.size(ofValue: localWifiAddress))
       localWifiAddress.sin_len            = UInt8(MemoryLayout.size(ofValue: localWifiAddress))
       localWifiAddress.sin_family         = sa_family_t(AF_INET)
       // IN_LINKLOCALNETNUM is defined in <netinet/in.h> as 169.254.0.0
       localWifiAddress.sin_addr.s_addr    = (IN_LINKLOCALNETNUM).bigEndian

       guard let reachabilityRef = withUnsafePointer(to: &localWifiAddress, {
           $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
               SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault, $0)
           }
       }) else {
           return nil
       }
       
       // code crashes if CFBridgingRetain is not called.
       CFBridgingRetain(reachabilityRef)
       
       // the init calls a CFBridgingRelease(reachability)
       return AFNetworkReachabilityManager.init(reachability: reachabilityRef)
   }