title: How to Create & Add an Core-Data Object to an Existing Object Having an Optional To-One Relationship?
body: <p>I cannot find any information anywhere (google, cocoadev, developer.apple) about managing an optional to-one relationship with core data and cocoa bindings with the exception of using a pop-up box. Using a pop-up box assumes the optional object already exists, but that's not how I want the process to work. I want to be able be able to select an existing object (User) in the table view and click an add button which would then create an new entity (Account) and assign the relationship to the selected User. In my model not all Users have an Account, and an Account is never created without having a User first. </p>
  
  <p>Any ideas on how to do this?</p>
  
  <p>I have tried to create a NSArrayController with the following:</p>
  
  <p>Bind to: UserController
  Controller Key:selection
  Model Key Path: Account</p>
  
  <p>I then bound a button to the -add function. When I do this I get: </p>
  
  <p>[NSCFSet managedObjectContext]: unrecognized selector sent to instance 0x1001adea0</p>
  
  <p>Please help I have spent days trying to figure this out.</p>