CollectionViewCell loading with nil value after reloadData func - swift

Question

I made a function to fetch data for an empty array that I'm using for a collectionView. I'm pulling the information from two different child nodes. The first being the "users" tree and the second being the "profile_images", using the UID from users to find the corresponding images. The cell populates when the view loads. My issue is that when the cell populates, I'm getting a nil value for one of the values.
I tried to add the array to the collectionViewCell instead of the view controller. I've also been reading the developer notes on prefetching data but it makes it seems like it's used for cells that have yet to be loaded.
var matches = [MatchData]()
// function to retrieve firebase data
private func populateInbox() {
if let uid = Auth.auth().currentUser?.uid {
// Supply Matches for users first
let match = MatchData()
Database.database().reference().child("users").observe(.childAdded) { (snapshot) in
let matichUID = snapshot.key
if matichUID != uid {
Database.database().reference().child("profile_images").child(matichUID).observeSingleEvent(of: .value, with: { (data) in
if let imageDict = data.value as? [String: AnyObject] {
match.matchImage = imageDict["imageOne"] as? String
print(match.matchImage)
}
})
if let dictionary = snapshot.value as? [String: AnyObject] {
print(uid, dictionary)
match.matchName = dictionary["firstName"] as? String
self.matches.append(match)
}
}
DispatchQueue.main.async {
self.matchList.reloadData()
print(self.matches.count)
}
}
}
}
// function to convert image url into UIImage
private func icon(_ imageURL: String, imageView: UIImageView) {
let url = URL(string: imageURL)
var image: UIImage?
var imageData:Data?
if url == nil {
print("Code failed here...")
imageView.image = #imageLiteral(resourceName: "ic_person_outline_white_2x")
} else {
URLSession.shared.dataTask(with: url!) { (data, response, error) in
if error != nil {
print("error")
DispatchQueue.main.async {
imageView.image = UIImage(imageLiteralResourceName: "ic_person_outline_white_2x")
}
} else {
DispatchQueue.main.async {
imageData = data
image = UIImage(data: imageData!)
imageView.image = image!
}
}
}.resume()
}
}
// Data model
class MatchData: NSObject {
var matchImage: String?
var matchName: String?
}
// additional details
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "InboxCell", for: indexPath) as! InboxCell
let matchInfo = matches[indexPath.row]
cell.userLabel.text = matchInfo.matchName
icon(matchInfo.matchImage ?? "", imageView: cell.userImage)
//icon always returns nil value but Userlabel returns name value
return cell
}
The expected result is to have a cell that displays images along with the name of the user the image belongs too. The actual results is the name of the users profile and a nil value for the image.

Answer 1

It looks like you append match to your matchlist before your observeSingleEventOf callback completes. Match updates when the image is received, but has already been added.
if let dictionary = snapshot.value as? [String: AnyObject] {
match.matchName = dictionary["firstName"] as? String
}
if matchUID != uid {
Database.database().reference().child("profile_images").child(matichUID).observeSingleEvent(of: .value, with: { (data) in
if let imageDict = data.value as? [String: AnyObject] {
match.matchImage = imageDict["imageOne"] as? String
}
self.matches.append(match)
DispatchQueue.main.async {
self.matchList.reloadData()
}
})
} else {
self.matches.append(match)
DispatchQueue.main.async {
self.matchList.reloadData()
}
}