Swift - 如何在Firebase上按降序创建排序查询? [英] Swift - How to create Sort query as Descending on Firebase?
问题描述
我坚持创建降序查询试图做和搜索,但我找不到可能的描述。这是我在Firebase上的 ref_post 测试。
$ b childByAutoId()
- userUid
- imageUrl
- timestamp(我使用这个)
*使用 NSDate()。formattedISO8601 是最好的方法还是可以建议我来处理它? / p>
如何在Firbase IOS / Swift中执行降序查询。这是我的 viewDidLoad :
$ b
let query = DataService.ds.REF_POSTS.queryOrderedByChild(timestamp)
query.observeEventType(.Value,withBlock:{snapshot in
if snapshots = snapshot.children.allObjects as?[FDataSnapshot] {
self.posts = $] b $ b为快照捕捉{
如果让postDict = snap.value为?Dictionary< String,AnyObject> {
print(postDict)
let post = Post(imageUrl:postDict [imageUrl]!as?String,username:DataService.ds.REF_USERS.authData.uid)
self.posts.append(post)
self.tableView.reloadData()
}
})
self.posts = self.posts.reverse()
保存 NSDate
我个人使用 timeIntervalSinceReferenceDate()
,它返回一个 NSTimeInterval
(这是一个 / code>),然后您可以保存在Firebase中。当读取数据时,可以用
init(timeIntervalSinceReferenceDate:)
获取原始 NSDate
。
I'm using Firebase with Alamofire, AlamofireImage to cache my imageURL data on memory and upload ImageShack.
I stuck creating descending query tried to do and search but I couldn't find possible description for me. Here's my test ref_post on Firebase.
childByAutoId()
-- userUid
-- imageUrl
-- timestamp (I have created using this)
*Using NSDate().formattedISO8601 Is it best way or Can you advice me to handle it basically?
How Can I do descending query in Firbase IOS/Swift. Here's my viewDidLoad:
let query = DataService.ds.REF_POSTS.queryOrderedByChild("timestamp")
query.observeEventType(.Value, withBlock: { snapshot in
if let snapshots = snapshot.children.allObjects as? [FDataSnapshot] {
self.posts = []
for snap in snapshots {
if let postDict = snap.value as? Dictionary<String, AnyObject> {
print(postDict)
let post = Post(imageUrl: postDict["imageUrl"]! as? String, username: DataService.ds.REF_USERS.authData.uid)
self.posts.append(post)
}
}
self.tableView.reloadData()
}
})
self.posts = self.posts.reverse()
To save NSDate
instances, I personally use timeIntervalSinceReferenceDate()
which returns an NSTimeInterval
(which is a Double
), which you can then save in Firebase. When reading the data, you can obtain the original NSDate
with init(timeIntervalSinceReferenceDate:)
.
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