title: Core Data: Passing a managed object to a class
body: <p>I have an app that stores product data in Core Data. I have a popover controller where you select a client, it calls back to the root view controller through Notification Center and then root vc gets that clients purchase agreement from core data. We store it as a property of the vc (workingPA). </p>
  
  <p>That purchase agreement data is then displayed. We have a calculator class (subclass of NSObject) and when the user makes edits to the PA it fires up and runs a bunch of calculations, getting base figures from the PA managed object we retrieved from Core Data. We're passing the PA to the calculator class from the root vc like so:</p>
  
  <p>calculator.workingPA = self.workingPA</p>
  
  <p>My question is this an acceptable way to pass a Core Data object to another class or is there another, "best practice" to accomplish this?  </p>