Question

因此，我有一个用户将发布的Feed，并希望每个新提交都转到我的集合视图的顶部。我按照此处显示的UTC时间的负值，按降序时间对每个新帖子进行排序：How do you properly order data from Firebase chronologically。

    "Posts" : {
      "-KHLOy5mOSq0SeB7GBXv" : {
           "timestamp" : "1476028495915",
           "descendStamp": "-1476028495915"
           "otherData": ""
       },
      "-KHLrapS0wbjqPP5ZSUY" : {
           "timestamp" : "1476028496102"
           "descendStamp" : "-1476028496102"
           "otherData": ""
       },

但是，添加的每个新实时帖子在最初加载时都会被置于底部。相信这是因为观察者只是异步加载新添加的孩子，而不是再次下载任何其他信息，这导致他忽略了我的

    .queryOrderedByChild("descendStamp")

离开并返回视图后，它会将最近添加的帖子正确组织到顶部。我是否需要客户端过滤才能实时获取这些新帖？或者，当新的帖子进入时，重新组织帖子顺序的最佳方法是什么？

    var posts = [PostModel]()

    let postQuery = ref.child("Posts").queryOrderedByChild("descendStamp")
        postQuery.observeEventType(.ChildAdded, withBlock: { (snap) in


            if snap.exists() {
                let postData = snap.value! as! [String: AnyObject]

                let post = PostModel()

                post.timestamp = postData["timestamp"] as? NSTimeInterval
                post.descendStamp = postData["descentStamp"] as? NSTimeInterval
                post.otherData = postData["otherData"] as? String

                self.posts.append(post)

                dispatch_async(dispatch_get_main_queue(), {
                    self.collectionView!.reloadData()
                })
            }

Answer 1

在更新tableView之前，只需对dataSource进行排序。

self.posts.sort(by: {$0.descendStamp > $1.descendStamp})

您的代码看起来像这样： -

var posts = [PostModel]()

let postQuery = ref.child("Posts").queryOrderedByChild("descendStamp")
    postQuery.observeEventType(.ChildAdded, withBlock: { (snap) in


        if snap.exists() {
            let postData = snap.value! as! [String: AnyObject]

            let post = PostModel()

            post.timestamp = postData["timestamp"] as? NSTimeInterval
            post.descendStamp = postData["descentStamp"] as? NSTimeInterval
            post.otherData = postData["otherData"] as? String

            self.posts.append(post)
            self.posts.sort(by: {$0.descendStamp > $1.descendStamp})

            dispatch_async(dispatch_get_main_queue(), {
                self.posts.sort(by: {$0.descendStamp > $1.descendStamp})
                self.collectionView!.reloadData()
            })
        }

按降序时间过滤时，向Firebase观察者添加新帖子

1 个答案: