Cell images are showing out of order, why is this happening?

Question

I'm building out a image feed that includes an image followed by a username label inside of a table view. For some reason, the cell images don't match the correct usernames. It almost seems that the images are downloaded in a different order than the usernames, but that can't be the case. Please help!

EDIT: After doing some console logging, I see that the images are downloaded and appended to the images array, in an different order than the usernames. BUT I don't know why, nor how to fix it.

import UIKit

class TrendingChallengeTableViewCell: UITableViewCell {


    @IBOutlet var postImage: UIImageView!

    @IBOutlet var postComment: UILabel!


    override func prepareForReuse() {
        super.prepareForReuse()

        self.postImage.image = nil
        self.postComment.text = ""
    }
}



import UIKit
import Parse

var pressedChallenge: String?

class TrendingChallengeTableViewController: UITableViewController {

    var images = [PFFile]()
    var usernames = [String]()



    override func viewDidLoad() {
        super.viewDidLoad()

        navigationItem.hidesBackButton = true

        let query = PFQuery(className: "Post")
        query.whereKey("imageComment", equalTo: pressedChallenge!)
        query.findObjectsInBackgroundWithBlock { (object, error) -> Void in

            self.usernames.removeAll(keepCapacity: true)
            self.images.removeAll(keepCapacity: true)

            if let object = object {
                for images in object {
                    self.images.append(images["imageFile"] as! PFFile)

                    let userQuery = PFUser.query()

                    userQuery?.whereKey("_id", equalTo: images["userId"])
                    userQuery?.findObjectsInBackgroundWithBlock({ (object, error) -> Void in
                        if let object = object {
                            for user in object {
                                self.usernames.append(user["username"] as! String)
                                self.tableView.reloadData()
                            }
                        }
                    })


                }
            }
        }

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    // MARK: - Table view data source

    override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
        // #warning Incomplete implementation, return the number of sections
        return 1
    }

    override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        // #warning Incomplete implementation, return the number of rows
        return usernames.count
    }


    override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        let trendCell = tableView.dequeueReusableCellWithIdentifier("trendingCell", forIndexPath: indexPath) as! TrendingChallengeTableViewCell

         trendCell.postComment.text = "\(usernames[indexPath.row]) completed the \(pressedChallenge!) challenge!"

        images[indexPath.row].getDataInBackgroundWithBlock { (data, error) -> Void in
            if let downloadedImage = UIImage(data: data!) {
              trendCell.postImage.image = downloadedImage
            }
        }



        return trendCell
    }


}

score 0 · Answer 1 · answered Feb 22 '16 at 18:24

0

Try telling both your queries to sort in a specific way before fetching the objects, ie:

let query = PFQuery(className: "Post")
query.whereKey("imageComment", equalTo: pressedChallenge!)
query.orderByDescending("createdAt")
query.findObjectsInBackgroundWithBlock { (object, error) -> Void in
    //etc
}

Do this for the second query as well.

answered Feb 22 '16 at 18:24

yesthisisjoe

1,987
2
16
32

Not sure how this would work. The first query looks for image files, the second one finds the usernames in a separate table that posted the image. I'm not seeing what kind of sort would happen for the user query, as there is no createdAt field. – Darryl Nunn Feb 22 '16 at 20:31
Have you tried it? I'm pretty sure all Parse objects have a createdAt field by default. – yesthisisjoe Feb 22 '16 at 20:50
Yes this is correct, however, when the users where created has no relation to when the user posted the image. I just tried it to see and it was a horrible result. Anything else you can think of? – Darryl Nunn Feb 22 '16 at 20:56

Cell images are showing out of order, why is this happening?

1 Answers1