title: How to serialize NSManagedObject to JSON in restkit 0.20?
body: <p>How to serialize NSManagedObject to JSON in restkit 0.20 using inverse mapping?</p>
  
  <p>Right now I don't need to post anything anywhere.</p>
  
  <p>I would like manually create object MyObjectManaged.
  Set some attributes for example:
  id,
  name,
  age</p>
  
  <p>Map them with existing mapping my mapping to JSON attributes:
  userid,
  first_name,
  age</p>
  
  <p>create and print JSON.</p>
  
  <p>Is it possible? When yes, how?
   Thank you in advance for your answer.</p>