Fetching data unordered with predicate from array - ios

Question

Here is function where I try to fetch images from parse for users that are in the namesArray.
func fetchData(){
let imagePredicate = NSPredicate(format: "username IN %#", namesArray)
let imageQuery = PFQuery(className: "_User", predicate: imagePredicate)
imageQuery.findObjectsInBackgroundWithBlock { (objects: [PFObject]?, error: NSError?) -> Void in
if error == nil {
for object in objects! {
self.imagesArray.append(object["image"] as! PFFile)
if self.imagesArray.count == self.namesArray.count {
self.tableView.reloadData()
}
} else {
print("error: \(error?.localizedDescription)")
}
}
}
Here is my tableView:cellForRowAtIndexPath method:
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("Cell") as! ChatsCell
cell.nameLabel.text = namesArray[indexPath.row]
if imagesArray.count == namesArray.count && self.imagesLoaded == false{
imagesArray[indexPath.row].getDataInBackgroundWithBlock { (imageData: NSData?, error: NSError?) -> Void in
if error == nil {
let image = UIImage(data: imageData!)
cell.imageView?.image = image
self.tableView.reloadData()
self.imagesLoaded = true
}
}
}
return cell
}
But when I do so I see that images are not synchronised with names of the users. Even if I put my users in other order images will stay in the same order as they was before.
How can I change it?

Answer 1

Not sure what you're asking here. Is it that you were expecting the images to be returned in an array sorted by the user?
If so, then you will need to add a sort order to your PFQuery. I suggest you sort your namesArray by username, and then also sort the imageQuery by username:
imageQuery.orderByDescending("username")
Hope I understood the question ;]
--T

Answer 2

So I found that if you use one query you will receive ordered data so I've changed my code and now it works pretty well. So what I've done is that I do query for every separate member of the namesArray:
func fetchData() {
for index in 0..<self.namesArray.count {
let imagePredicate = NSPredicate(format: "username == %#", namesArray[index])
let imageQuery = PFQuery(className: "_User", predicate: imagePredicate)
imageQuery.findObjectsInBackgroundWithBlock({ (objects: [PFObject]?, error: NSError?) -> Void in
if error == nil {
for object in objects! {
self.imageFilesArray![index] = object["image"] as? PFFile
}
for imageFile in self.imageFilesArray! {
let index = self.imageFilesArray?.indexOf{$0 == imageFile}
imageFile?.getDataInBackgroundWithBlock({ (imageData: NSData?, error: NSError?) -> Void in
let userImage = UIImage(data: imageData!)
self.imagesArray?[index!] = userImage
self.tableView.reloadData()
})
}
}
})
}
}
and here is tableView:cellForRowAtIndexPath:
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("Cell") as! ChatsCell
cell.nameLabel.text = namesArray[indexPath.row]
cell.messageTextLabel.text = messagesArray[indexPath.row]
cell.chatImageView.image = self.imagesArray![indexPath.row] != nil ? self.imagesArray![indexPath.row] : UIImage(named: "add")
return cell
}