title: Core Data managed objects in swift - is nil allowed?
body: <p>I have created NSManagedObject subclasses for my model objects in swift.</p>
  
  <p>Typically my pattern is to create an instance of an object and then set properties on it, then save.</p>
  
  <p>The new objects have properties that are set to nil. They are not optionals, though. I thought in swift this wasn't allowed?</p>
  
  <p>A lot of times I need to check for values, but if I try something like:</p>
  
  <p>if (managedObject.property == nil) I crash.</p>