extension NSManagedObjectContext {
    //MARK: - Public Properties
    public class var defaultContext: NSManagedObjectContext! {
        get {
            let context = NSManagedObjectContext(concurrencyType: NSManagedObjectContextConcurrencyType.MainQueueConcurrencyType)
            context.persistentStoreCoordinator = self.persistentStoreCoordinator // This provided by more extension properties
            return context
        }
    }
}

extension NSManagedObject {
  override convenience init() {
        let entity = NSEntityDescription.entityForName("Person", inManagedObjectContext: NSManagedObjectContext.defaultContext) // Person will be replaced with utility property if I get this appraoch working
        self.init(entity: entity!, insertIntoManagedObjectContext: NSManagedObjectContext.defaultContext)
  }
}

public class Person: NSManagedObject {
    @NSManaged var name: String
    @NSManaged var dateOfBirth: NSDate
}

Unit test:

    func testCreateEntity() {
        let entity = Person() // <=== compile error: Missing argument for parameter 'entity' in call
        XCTAssertNotNil(entity, "entity should not be nil")
    }