Swift - Problems receiving images from parse and displaying them - ios

Question

I'm having issues fetching the users images from parse and loading them on a table view.. I think it is something to do with the userId /Strings and pointer buissness!
The images upload fine to parse and I can see them, but I cannot seem to download them. My code is definetly the problem, I just can't figure out which part.
On parse the userId is a pointer to the user class, so I'm pretty sure I've done something wrong connecting it all..! I'm new to swift & Parse so I still have a bit of difficulty understanding it all.
Here's my code below, if anyone understands the problem I would love it if you could tell me!!
import UIKit
import Parse
class TimelineTableViewController: UITableViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate, UIPopoverPresentationControllerDelegate {
#IBOutlet var feedTableView: UITableView!
var refresher:UIRefreshControl!
var titles = [String]()
var username = [String]()
var imageFiles = [PFFile]()
var users = [String: String]()
override func viewDidLoad() {
super.viewDidLoad()
let query = PFUser.query()
query?.findObjectsInBackgroundWithBlock({ (objects, error) -> Void in
if let users = objects {
self.titles.removeAll(keepCapacity: true)
self.imageFiles.removeAll(keepCapacity: true)
self.users.removeAll(keepCapacity: true)
self.username.removeAll(keepCapacity: true)
for object in users {
if let user = object as? PFUser {
self.users[user.objectId!] = user.username!
}
}
}
let getFollowedUsersQuery = PFQuery(className: "followers")
getFollowedUsersQuery.whereKey("follower", equalTo: PFUser.currentUser()!)
getFollowedUsersQuery.findObjectsInBackgroundWithBlock { (objects, error) -> Void in
if let objects = objects {
for object in objects {
let followedUser = object ["following"] as! String
let query = PFQuery(className: "Post")
query.whereKey("userId", equalTo: followedUser)
query.findObjectsInBackgroundWithBlock({ (objects, error) -> Void in
if let objects = objects {
for object in objects {
self.titles.append(object["title"]! as! String)
self.imageFiles.append(object["imageFile"]! as! PFFile)
self.username.append(self.users[object["userId"] as! String]!)
self.tableView.reloadData()
} }}) } } } })
// Add the refresher
refresher = UIRefreshControl()
refresher.attributedTitle = NSAttributedString(string: "")
refresher.addTarget(self, action: "refreshData", forControlEvents: UIControlEvents.ValueChanged)
// Add the refresher as a sub view on the tableview
self.feedTableView.addSubview(refresher)
}
func refreshData() -> Void {
self.refresher.endRefreshing()}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
#IBAction func blogPost(sender: AnyObject) {
}
#IBAction func CameraPopover(sender: AnyObject) {
self.performSegueWithIdentifier("cameraPopover", sender: self)
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "cameraPopover"
{
let vc = segue.destinationViewController
let controller = vc.popoverPresentationController
if controller != nil
{
controller?.delegate = self
vc.preferredContentSize = CGSizeMake(50, 90)
}
}}
func adaptivePresentationStyleForPresentationController(controller: UIPresentationController) -> UIModalPresentationStyle {
return.None
}
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 username.count
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let postCell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as! TimelineTableViewCell
imageFiles[indexPath.row].getDataInBackgroundWithBlock { (data, error) -> Void in
if let downloadedImage = UIImage(data: data!) {
postCell.postedImage.image = downloadedImage
}
}
postCell.usernameLabel.text = username[indexPath.row]
postCell.titleLabel.text = titles[indexPath.row]
return postCell
}
}

Answer 1

The issue you mentioned with the userId pointer is here:
let followedUser = object ["following"] as! String
let query = PFQuery(className: "Post")
query.whereKey("userId", equalTo: followedUser)
You mentioned that the userId column of the Post class is a User pointer, however you reference it as a string with followedUser.
With regards to the images not displaying properly, they will not be displayed until you refresh the UI. You are using the correct code to load the data which is
imageFiles[indexPath.row].getDataInBackgroundWithBlock { (data, error) -> Void in
if let downloadedImage = UIImage(data: data!) {
postCell.postedImage.image = downloadedImage
}
However, the issue is that since the data is loaded asynchronously, the postCell will be returned to the table before the data has been fetched. The key piece that's missing is to refresh the table using self.tableView.reloadData() in the completion handler.
imageFiles[indexPath.row].getDataInBackgroundWithBlock { (data, error) -> Void in
if let downloadedImage = UIImage(data: data!) {
postCell.postedImage.image = downloadedImage
self.tableView.reloadData()
}
Alternatively, I would recommend looking into using a PFImageView from the ParseUI framework. You assign each of the PFFiles to a PFImageView in the completion of the query and then call loadInBackground on each PFImageView. The PFImageView class automatically handles updating the images once the data has been loaded.