未从 Firebase 存储加载的用户图像

Question

运行此代码时，我只从资产返回UIImage(named: "Home Button")，而不是每个用户选择的图片？任何想法为什么？？

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

我认为您的代码有两个问题可能会有所帮助。首先，从 Firebase 存储加载图像时使用 SD WebImage 被认为是最佳做法。 SD WebImage会处理异步加载图片，缓存图片，保证同一个URL不会被多次下载，虚假URL不会被重试。 SD WebImage 随 Firebase 一起提供，因此您需要做的就是确保已将 Storage 添加到 PodFile 并在 TableViewController 中为 SDWebImage 和 FirebaseStorage 创建导入。然后你应该把你的 cellForRowAt indexPath 修改成这样：

    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
}

其次，您在哪里为每个用户设置个人资料图片？我可以看到您设置显示名称和字幕状态，但我看不到您在哪里添加个人资料图像。也许您打算执行以下操作：

    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)