title: Retrofit when activity is destroyed
body: <p>I see different examples regarding retrofit (Performing restapi from android) where they write the code/put the callback in the activity as in the following link: 
  I was wondering whether this is a correct approach ? I read that problems could be triggered if the activity is destroyed due to a phone call for example.
  If this is correct, I would appreciate an explanation why the destruction of the activity does not influence application ?</p>
  
  <p>Thanks,
  Clint</p>