我有两个名为Followers和Posts的课程，我正在尝试制作主屏幕，通过该主屏幕，我可以看到我关注的用户发布的帖子，以及我的帖子帖子也是..所以我试着这个来查询帖子：
func loadData() {
var postQuery:PFQuery = PFQuery(className: "Posts")
postQuery.orderByDescending("createdAt")
postQuery.findObjectsInBackgroundWithBlock { (objects, error) -> Void in
if let objects = objects {
for object in objects {
self.data.addObject(object)
println(object.createdAt)
self.tableView.reloadData()
}
}
}
}
这里postQuery.orderByDescending("createdAt")工作正常.. println(object.createdAt)给出了完美的结果：
Optional(2015-08-25 22:31:12 +0000)
Optional(2015-08-25 22:28:28 +0000)
Optional(2015-08-25 22:25:36 +0000)
Optional(2015-08-24 13:40:48 +0000)
Optional(2015-08-24 13:39:25 +0000)
如果我也尝试查询被跟踪的用户，请执行以下操作：
func loadData() {
let postsByCurrentUser = PFQuery(className: "Posts")
postsByCurrentUser.orderByAscending("createdAt")
postsByCurrentUser.whereKey("postedBy", equalTo: PFUser.currentUser()!)
postsByCurrentUser.findObjectsInBackgroundWithBlock ({ (objects, error) -> Void in
if let posts = objects as? [PFObject] {
for post in posts {
}
}
})
var posts:PFQuery = PFQuery(className: "Followers")
posts.whereKey("follower", equalTo: PFUser.currentUser()!)
posts.findObjectsInBackgroundWithBlock { (objects, error) -> Void in
if let objects = objects {
for object in objects {
var followedId = object["user"] as! PFObject
var postsByFollowedUser:PFQuery = PFQuery(className: "Posts")
postsByFollowedUser.whereKey("postedBy", equalTo: followedId)
postsByFollowedUser.findObjectsInBackgroundWithBlock({ (objects, error) -> Void in
if let objects = objects {
for object in objects {
}
}
})
}
}
}
}
使用此代码，我获得了帖子的随机顺序。 我在哪里错了..如果你需要任何关于我可以给你的问题的解释但是在这里帮助我..我无法找到错误。所以基本上：
我想根据时间在orderByDescending中获取帖子。
我在这里收到当前用户所关注的用户的帖子，但是当前用户的帖子。我该怎么做？
答案 0 :(得分：0)
首先，我是Android开发人员并且不做iOS，但我认为我得到了你想做的事情，所以请相应地翻译它。您可能希望查看ParseQuery.whereMatchesQuery（）。基本上你会有2个查询：一个是主要查询的帖子，另一个是关注者的帖子。
// Query to find followers of current user
ParseQuery<ParseObject> queryFollowers = ParseQuery.getQuery("Followers");
queryFollowers.whereMatches("follower", currentUser.getId());
// Query to find posts
ParseQuery<ParseObject> postQuery = ParseQuery.getQuery("Posts");
// Retrieves posts which statisfies the first query (followers of current user)
postQuery.whereMatchesQuery("postedBy", queryFollowers);
postQuery.orderByDescending("createdAt");
// Objects returned here are the posts by followers
postQuery.findInBackground...
答案 1 :(得分：0)
所以这里是完整的答案..
我知道它不是最优化的代码（你可以将它重构为方法）但是它给你想要的结果......
--- Sorted posts by current user
Optional(Test)
Optional(Test1)
Optional(Test2)
Optional(Test3)
Optional(Test4)
Optional(Test20)
--- Sorted posts by every follower
Optional(Test10)
Optional(Test11)
Optional(Test12)
完整的代码在这里：
override func viewDidLoad() {
super.viewDidLoad()
if PFUser.currentUser() != nil {
PFUser.logOut()
}
PFUser.logInWithUsernameInBackground("test", password: "test") { (let currentUser, let error) -> Void in
println("---")
// Insert test post
// let testPost = PFObject(className: "Posts")
// testPost["post"] = "Test20"
// let userRelation : PFRelation = testPost.relationForKey("postedBy")
// userRelation.addObject(PFUser.currentUser()!)
// testPost.saveEventually()
// Insert test relation
// let userToFollow = PFUser.query()
// userToFollow?.whereKey("username", equalTo: "test1")
// userToFollow?.findObjectsInBackgroundWithBlock({ (let result, let error) -> Void in
//
// if let follower = result!.first! as? PFUser {
//
// let followers = PFObject(className: "Followers")
// let userRelation : PFRelation = followers.relationForKey("user")
// userRelation.addObject(PFUser.currentUser()!)
// let followerRelation : PFRelation = followers.relationForKey("follower")
// followerRelation.addObject(follower)
//
// followers.saveEventually()
// }
// })
// Get posts by currentUser
let postsByCurrentUser = PFQuery(className: "Posts")
postsByCurrentUser.orderByAscending("createdAt")
postsByCurrentUser.whereKey("postedBy", equalTo: PFUser.currentUser()!)
postsByCurrentUser.findObjectsInBackgroundWithBlock({ (let pfPosts, let error) -> Void in
if let posts = pfPosts as? [PFObject] {
for post in posts {
println(post["post"])
}
}
})
// Get posts by followers
let postsByCurrentUserFollowers = PFQuery(className: "Followers")
postsByCurrentUserFollowers.whereKey("user", equalTo: PFUser.currentUser()!)
postsByCurrentUserFollowers.findObjectsInBackgroundWithBlock({ (let pfFollowers, let error) -> Void in
if let followers = pfFollowers as? [PFObject] {
for follower in followers {
let userFollowerRelation = follower.relationForKey("follower")
userFollowerRelation.query()!.findObjectsInBackgroundWithBlock({ (let followerToUser, let error) -> Void in
if let followerUser = followerToUser!.first! as? PFUser {
let postsByCurrentUser = PFQuery(className: "Posts")
postsByCurrentUser.orderByAscending("createdAt")
postsByCurrentUser.whereKey("postedBy", equalTo: followerUser)
postsByCurrentUser.findObjectsInBackgroundWithBlock({ (let pfPosts, let error) -> Void in
if let posts = pfPosts as? [PFObject] {
for post in posts {
println(post["post"])
}
}
})
}
})
}
}
})
}
}