title: implement delegation from a viewController to a DataManager class
body: <p>I need to send an object (data) from a view controller (embedded in a navigation controller) to a class (or struct) which should manage this data. 
  How can I get a reference to this viewController from the class (which has no link of any kind (no segue), or better the struct)  with the set of viewControllers in order to implement a delegation protocol? </p>
  
  <p>I use swift, a storyboard, and I look for any pointer or documentation which could help me to understand how to address this problem. I'm a beginner and I am sorry if this question is far too trivial. </p>
  
  <p>I just need a link to appropriate documentation, many thanks. </p>