ios - localizedFailureReason returns null -

I need to show error localized failure for some reason I am receiving NSERR

  error domain = NSCKeardom code = 3840 "operation could not be completed (coco error 3840.)" (Unexpected end of file during parsing the object.) UserInfo = 0x178a72b80 {NSDebugDescription = Unexpected end of file while parsing the object.}  

When I try to log in

  [Error localized Failure] cause  

I am getting zero value for this. Do I know what is the reason? I'm only getting

  The operation could not be completed. (COCAIAA error 3840.)  
  for [error localized description] only  
 
 my complete code below Method of: 
 
  + (NSDictionary *) insertErrorIntoFormat: (NSError *) error {NSLog (@ "1.% @", [error localized description]); NSLog (@ "2.% @", [description of error]); NSLog (@ "3.% @", [self will getDateStringString]); NSDictionary * threat = [NSDiction dictionary with object and case: [self-matching catastrophe stretching], KTMstamp, [error localized description], @ "log", [error localized failure], @ "cause", zero]; Return threat; An NSError does not need to be a failure reason string.  
 

zero before you need to check the return value before adding it to NSDRA or NSERRA, because those data structures can not have any zero value.