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我已经建立了我的火力点在图片中,现在我想通过比较每个岗位时间戳只新帖养活我的帖子,我已经写了下面我该怎么做queryOrdered(bychild)呢?
func getRecentPosts(start timestamp: Int? = nil, limit: UInt, completionHandler: @escaping (([Post]) -> Void)){
let POST_DB_REF: DatabaseReference = Database.database().reference().child("posts")
var allPosts = POST_DB_REF.queryOrdered(byChild: "timestamp")
if let latestPostTimestamp = timestamp, latestPostTimestamp > 0 {
//If the timestamp is specified, we will get the posts with timestamp newer than the given value
allPosts = allPosts.queryStarting(atValue: latestPostTimestamp + 1, childKey: Post.PostInfoKey.timestamp).queryLimited(toLast: limit)
} else {
//Otherwise, we will just get the most recent posts
allPosts = allPosts.queryLimited(toLast: limit)
}
//Call Firebase API to retrieve the latest records
allPosts.observeSingleEvent(of: .value, with: { (snapshot) in
var newPosts: [Post] = []
for userPosts in snapshot.children.allObjects as! [DataSnapshot] {
for eachPost in userPosts.children.allObjects as! [DataSnapshot] {
let postInfo = eachPost.value as? [String:Any] ?? [:]
if let post = Post(postId: eachPost.key, postInfo: postInfo) {
newPosts.append(post)
}
}
}
if newPosts.count > 0 {
//Order in descending order (i.e. the latest post becomes the first post)
newPosts.sort(by: {$0.timestamp > $1.timestamp})
}
completionHandler(newPosts)
})
}
代码这里是我的火力配置。 FIREBASE 这与第一次运行,然后如果我发布一个新的饲料它没有得到更新,任何想法? 在此先感谢。
如何getRecentPosts被称为?错误可能是这个方法没有被调用? –
是的,我在我的FeedTableViewController中调用此方法添加新帖子。 –
实际上,在ViewDidLoad和每次发布内容时都会调用两种方法。 –