I would like to have this be an abstract class.

gistfile1.txt

class Entity: NSObject
{
	var objectID: String?
	var createdAt: NSDate?
	var updatedAt: NSDate?
	
	required override init()
	{
	}
	
	required init(dictionary: Dictionary<String, AnyObject>)
	{
		if let objectID = dictionary["objectId"] as? String
		{
			self.objectID = objectID
		}

		if let createdAt = dictionary["createdAt"] as? String
		{
			self.createdAt = NSDate.dateFromJSONDateString(createdAt)
		}

		if let updatedAt = dictionary["updatedAt"] as? String
		{
			self.updatedAt = NSDate.dateFromJSONDateString(updatedAt)
		}
	}
	
	func dictionaryRepresentation() -> Dictionary<String, AnyObject>
	{
		var dict = Dictionary<String,String>()
		
		if let objectID = objectID
		{
			dict["objectId"] = objectID
		}
		
		if let createdAt = createdAt
		{
			dict["createdAt"] = createdAt.JSONDateString()
		}

		if let updatedAt = updatedAt
		{
			dict["updatedAt"] = updatedAt.JSONDateString()
		}

		return dict
	}
}