无法从Firebase存储加载用户图像

Question

when running this code I only get it returning UIImage(named: "Home Button") from assests and not each user's chosen picture? Any ideas why??

class usersScreenVC: UITableViewController {

let cellId = "cellId"

var users = [User]()

override func viewDidLoad() {
    super.viewDidLoad()

    navigationItem.leftBarButtonItem = UIBarButtonItem(title: "Cancel", style: .plain, target: self, action: #selector(handleCancel))

    tableView.register(UserCell.self, forCellReuseIdentifier: cellId)

    fetchUser()
}

func handleCancel() {
    self.dismiss(animated: true, completion: nil)
}

func fetchUser() {
    FIRDatabase.database().reference().child("Users").observe(.childAdded, with: { (snapshot) in

        if let dictionary = snapshot.value as? [String: AnyObject] {
            let user = User()

            self.users.append(user)

            user.DisplayName =  dictionary["Display Name"] as? String
            user.SubtitleStatus = dictionary["SubtitleStatus"] as? String

            DispatchQueue.main.async {
                self.tableView.reloadData()
            }
        }
    }, withCancel: nil)
}

override      func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return users.count

}

 override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {


           let cell = UITableViewCell(style: .subtitle, reuseIdentifier: cellId)

    let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath)

    let user = users[indexPath.row]
    cell.textLabel?.text = user.DisplayName
    cell.detailTextLabel?.text = user.SubtitleStatus

    cell.imageView?.image = UIImage(named: "Home Button")

    if let profileImageURL = user.profileImageURL{
        let url = URL(string: profileImageURL)


       URLSession.shared.dataTask(with: url!, completionHandler: { (data, response, error) in     
            //this mean download hit an error so lets return out.
            if error != nil {
                print(error!)
                return
            }

            DispatchQueue.main.async(execute: {     
                cell.imageView?.image = UIImage(data: data!)
            })      
        }).resume()
    }

    return cell
}

class UserCell: UITableViewCell {

override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
    super.init(style: .subtitle, reuseIdentifier: reuseIdentifier)
}

required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

}
}//class

Answer 1

There are about two issues with your code that I think might help. First of all, it is considered best practice to use SD WebImage when loading images from Firebase Storage. SD WebImage will deal with asynchronously loading images, caching images, guarantee that the same URL won't be downloaded several times and bogus URLs won't be retried. SD WebImage comes with Firebase so all you need to do to make it work is to make sure you have added Storage to your PodFile and to create an import for SDWebImage and FirebaseStorage in your TableViewController. Then you should modify your cellForRowAt indexPath to something like this:

    import SDWebImage
    import FirebaseStorage 

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {


       let cell = UITableViewCell(style: .subtitle, reuseIdentifier: cellId)

       let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath)

        let user = users[indexPath.row]
        cell.textLabel?.text = user.DisplayName
        cell.detailTextLabel?.text = user.SubtitleStatus

        cell.imageView?.image = UIImage(named: "Home Button")

        if let profileImageURL = user.profileImageURL{
        let url = URL(string: profileImageURL)

        cell.imageView?.sd_cancelCurrentImageLoad()

        cell.imageView?.sd_setImage(with: url, completed: { (image, error, type, url) in
        DispatchQueue.main.async {
        cell.layoutSubviews()
        }
    })      

}

return cell
}

Second of all, where are you setting the profile image for each user? I can see you setting the display name and subtitle status but I cannot see where you are adding the profile image. Perhaps you meant to do something like the following:

    if let dictionary = snapshot.value as? [String: AnyObject] {
        let user = User()

        self.users.append(user)

        user.DisplayName =  dictionary["Display Name"] as? String
        user.SubtitleStatus = dictionary["SubtitleStatus"] as? String

        //did you forget to add the profile image url like this?
       user.profileImageURL = dictionary["ProfileImage"] as? String

        DispatchQueue.main.async {
            self.tableView.reloadData()
        }
    }
}, withCancel: nil)