ios – Firebase查询错误处理

我有一些函数可以从Firebase读取数据,但有时候我从来没有得到过响应(或者它被大量延迟).我读了 here,Firebase可能会在收到数据之前关闭套接字连接.看起来有人有类似的问题 here,但从未发布过解决方案.

以下是我从Firebase下载用户数据的代码示例.

// loads the current user's information
static func loadUserDataWithCompletion(completion: (UserInfo) -> Void) {
    let ref = FIRDatabase.database().reference()
    print("loading current user data...")

    let uid = (FIRAuth.auth()?.currentUser?.uid)!
    ref.child("users").queryorderedByKey().queryEqualToValue(uid).observeEventType(.ChildAdded,withBlock: { (snapshot) in

        print("found user data!")
        if let Dictionary = snapshot.value as? [String:AnyObject] {
            let info = userFromDict(Dictionary)

            // execute code slated for completion
            completion(info)
        }
    })
}

有没有办法可以使用observeEventType检测错误？也许那时我至少会获得有关问题发生原因的更多信息.

FIRDatabase.database().reference().child("users").queryorderedByKey().queryEqual(toValue: "uid").observe(.childAdded,with: { (snapshot) in
        //your code
        },withCancel: {(err) in

            print(err) //The cancelBlock will be called if you will no longer receive new events due to no longer having permission.

    })