快速解析查询获取最后一个 createdAt 对象 [英] swift parse query get last createdAt objects

问题描述

我做了很多查询，在网站上搜索过，之前已经问过这个问题，我没有找到好的答案！

I have did a lot of querys, searched in websites , And already asked this question before and i didn't found a good answer!

我的 Parse 后端如下所示:

I have Parse backend looks like this:

在我的视图控制器中，我只想为每个发件人显示 Last createdAt我想为发件人获取最后一个对象的所有行:.

In my view controller I just want to show Last createdAt for each sender i want to get all the row of last object for sender:.

所以我们应该忽略name1:Hello"和name2:Really when was.."因为这些旧行我们已经有了新对象.

so we should ignore "name1: Hello" and "name2: Really when was.." because this old rows we already got new objects.

我希望每个发件人的结果取决于 createdAt

I want one result for each sender depends on createdAt

那么我可以通过查询获得帮助吗?或者我们怎么做?

so can I get help with query to do this? or how can we do that?

let query = PFQuery(className: "test")
        query.whereKey("receivers", equalTo: PFUser.currentUser()!.username!)
        query.orderByDescending("createdAt")
        query.findObjectsInBackgroundWithBlock {
            (objects, error) -> Void in

            if error == nil {

                // now what? I've done everything i could none worked fine

我希望我能得到帮助，所以如果可以，请帮助我.

I hope if i'll get a help to do that, So please help me if you could.

推荐答案

你可以只添加一个 limit 到查询中.. 见解析文档..

you can just add a limit to the query.. see parse docs..

 let query = PFQuery(className: "test")
    query.whereKey("receivers", equalTo: PFUser.currentUser()!.username!)
    query.orderByDescending("createdAt")
    query.limit = 1
    query.findObjectsInBackgroundWithBlock {
        (objects, error) -> Void in

        if error == nil {

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