Timestamps for Core Data Models

    override public func awakeFromInsert() {
        super.awakeFromInsert()
        let now = Date()
        self.setPrimitiveValue(now, forKey: "cd_created_at")

        self.cd_created_at = now
    }
    
    override public func willSave() {
        super.willSave()
        if !self.isDeleted && self.changedValues()["cd_updated_at"] == nil && self.changedValues().count > 0{
            self.cd_updated_at = Date()
        }
    }