错误：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中代理方法可选需要在前面加@objc
然后在加玩@objc后还是有上面的报错，
这是因为JJModel没有加@objc
所以需要
@objc class JJModel: NSObject {
}
