title: How to wait for a UIViewController to be completely initialized?
body: <p>I have a custom segue type (overriding init and perform methods of UIStoryboardSegue) and in init method I instantiate the destination view controller(VC). In prepareForSegue method of source VC I call a method of the destination VC that tries to reload the tableView of the destination VC. The problem is that the table view is not always initialized and I SOMETIMES get a nil de-reference error when I call the reloaddata of the tableview. 
  The question is that how can I wait till the VC is fully initialized and do not get this error? 
  I am using swift and would appreciate if you write any sample code for the answer in swift. </p>