錯誤：Method cannot be marked @objc because the type of the parameter 1 cannot be represented in Objective-C

@objc protocol JJViewDelegate: class {
    @objc optional func JJClicked(model: JJModel, isSelected: Bool)
}
swift4中代理方法可選需要在前面加@objc
然后在加玩@objc后還是有上面的報錯，
這是因為JJModel沒有加@objc
所以需要
@objc class JJModel: NSObject {
  }