swift 下LiveQuery订阅不到通知，后台也无看到消息

1：appID ：mOg90SURiMp7pkUNCH7VfRBp 2：平台：iOS： 13.0 3：sdk最新

private func initLiveQuery(){
print("init Live")
do {
let query = LCQuery(className: "Todo")

        let lQuery  = try LiveQuery(query: query, eventHandler: { (liveQuery, event) in
            switch event {
            case .create(object: let object):
                print(object["title"] as Any) // 更新作品集
            case .update(object: _, updatedKeys: _):
                print("对象被更新。")
            default:
                break
            }
        })
        lQuery.subscribe { (result) in
            print("sdf\(result)")
            switch result {
            case .success:
                print("success")
            case .failure(error: let error):
                print("failure")

                print(error)
            }
        }
    } catch {
        print("error")
        print(error)
    }
    
}

请问下有没有swift的livequery的Demo

我用的是swiftui， 代码改成
@State var liveQuery :LiveQuery = nil
private func initLiveQuery(){
print("init Live")
do {
let query = LCQuery(className: "Todo")

        if self.liveQuery == nil {
                self.liveQuery = try LiveQuery(query: query, eventHandler: { (liveQuery, event) in
                switch event {
                case .create(object: let object):
                    print(object["title"] as Any) // 更新作品集
                case .update(object: _, updatedKeys: _):
                    print("对象被更新。")
                default:
                    break
                }
            })
        }

        if self.liveQuery != nil {
            print("subscribe")
            self.liveQuery?.subscribe { (result) in
                print("sdf\(result)")
                switch result {
                case .success:
                    print("success")
                case .failure(error: let error):
                    print("failure")

                    print(error)
                }
            }
        }

    } catch {
        print("error")
        print(error)
    }
    
}

订阅时候报错：
LeanCloud.LCError(code: 1, reason: Optional("Invalid where."), userInfo: nil, underlyingError: nil))

添加了查询
query.whereKey("createdAt", .descending)
还是提示一样的"error": "Invalid where." 错误

        let query = LCQuery(className: "Todo")
        query.whereKey("createdAt", .descending)

这个我用来查询todo列表，是正常的，但是放到LiveQuery里面就是Optional("Invalid where.")错误，不明白你说的条件不合法具体错误是哪里？

        let query = LCQuery(className: "Todo")
        self.liveQuery = try LiveQuery(query: query, eventHandler: { (liveQuery, event) in })

ok，我的目的是这个Todo表数据有变化就订阅，就跟官网的需求一样，为什么也是报错啊。。官方没有提供一个demo吗？