Some cells won't show - ios

Question

I'm trying to create a chat applications with tableview to show the messages. Everything works fine except that some cells just won't show. It aren't always the same cells. I'm getting the messages from my Firebase database.
My Code:
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if let cell = cellCache.object(forKey: indexPath as AnyObject) as? UITableViewCell{
return cell
}
let cell = messagesTableView.dequeueReusableCell(withIdentifier: "otherMessageCell") as! OtherMessageTableViewCell
DispatchQueue.global(qos: .userInteractive).async {
let message = self.messages[indexPath.row]
let ref = FIRDatabase.database().reference()
let uid = FIRAuth.auth()?.currentUser?.uid
if(uid == message.sender) {
cell.sender.textAlignment = .right
cell.message.textAlignment = .right
}else{
cell.sender.textAlignment = .left
cell.message.textAlignment = .left
}
let uidReference = ref.child("Users").child(message.sender!)
uidReference.observeSingleEvent(of: .value, with: { (snapshot) in
if let dictionary = snapshot.value as? [String: AnyObject] {
let username = dictionary["Username"] as! String
let imageLink = dictionary["Image Link"] as! String
cell.sender.text = username
cell.message.text = message.message
cell.profileImage.image = nil
cell.profileImage.loadImageWithURLString(urlString: imageLink)
}
}, withCancel: nil)
}
DispatchQueue.main.async {
self.cellCache.setObject(cell, forKey: indexPath as AnyObject)
}
return cell
}
Example:
I hope someone will be able to help me. Thanks

Answer 1

I've found a solution:
var savedSenders = [Int: String]()
var savedMessages = [Int: String]()
var savedImages = [Int: UIImage]()
var savedAlignments = [Int: NSTextAlignment]()
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = messagesTableView.dequeueReusableCell(withIdentifier: "otherMessageCell") as! OtherMessageTableViewCell
if(savedSenders[indexPath.row] != nil && savedMessages[indexPath.row] != nil && savedImages[indexPath.row] != nil && savedAlignments[indexPath.row] != nil) {
cell.sender.textAlignment = savedAlignments[indexPath.row]!
cell.message.textAlignment = savedAlignments[indexPath.row]!
cell.sender.text = savedSenders[indexPath.row]
cell.message.text = savedMessages[indexPath.row]
cell.profileImage.image = savedImages[indexPath.row]
return cell
}
cell.sender.text = ""
cell.message.text = ""
cell.profileImage.image = nil
DispatchQueue.global(qos: .userInteractive).async {
let message = self.messages[indexPath.row]
let ref = FIRDatabase.database().reference()
let uid = FIRAuth.auth()?.currentUser?.uid
if(uid == message.sender) {
cell.sender.textAlignment = .right
cell.message.textAlignment = .right
self.savedAlignments.updateValue(.right, forKey: indexPath.row)
}else{
cell.sender.textAlignment = .left
cell.message.textAlignment = .left
self.savedAlignments.updateValue(.left, forKey: indexPath.row)
}
let uidReference = ref.child("Users").child(message.sender!)
uidReference.observeSingleEvent(of: .value, with: { (snapshot) in
if let dictionary = snapshot.value as? [String: AnyObject] {
let username = dictionary["Username"] as! String
let imageLink = dictionary["Image Link"] as! String
cell.sender.text = username
cell.message.text = message.message
cell.profileImage.image = nil
cell.profileImage.loadImageWithURLString(urlString: imageLink)
let url = URL(string: imageLink)
URLSession.shared.dataTask(with: url!) { (data, response, error) in
if(error != nil){
print(error as Any)
return
}
DispatchQueue.main.async {
if let downloadedImage = UIImage(data: data!) {
let image = downloadedImage
self.savedSenders.updateValue(username, forKey: indexPath.row)
self.savedMessages.updateValue(message.message!, forKey: indexPath.row)
self.savedImages.updateValue(image, forKey: indexPath.row)
}
}
}.resume()
}
}, withCancel: nil)
}
return cell
}
The data for every cell is saved into the arrays (savedSenders, savedMessages, savedImages and savedAlignments). If I don't save it into arrays, the cells will have to load all the data from Firebase and this will take longer. If it takes longer, it won't look good.
I tested everything and it works.