ios - 有时分配给 UITableViewCell 中的 UIImageView 的图像不正确

Question

我有一个有几百人的群聊，当我快速滚动时，有时用户图像会从某处跳到另一处，或者向用户显示不正确的图像。

我已经关注了其他一些帖子，但我似乎仍然做错了一些事情。这里有什么突出的地方吗？我可以做些什么来解决这个问题？

谢谢!

final class MessageCell: UITableViewCell {

    private lazy var profileImageView: UIImageView = {
        let imageView = UIImageView()
        imageView.layer.cornerRadius = 20
        imageView.clipsToBounds = true

        return imageView
    }()

    // MARK: – Init

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

        selectionStyle = .none

        addSubview(profileImageView)

        setupConstraints()
    }

    private func setupConstraints() {
        constrain(profileImageView) {
            let size: CGFloat = 36
            $0.width == size
            $0.height == size
            $0.bottom == $0.superview!.bottom - CGFloat(3)
            $0.left == $0.superview!.left + CGFloat(12)
        }
    }


    func configure(with presentable: CellPresentable) {
        self.presentable = presentable

        if let sender = presentable.sender, presentable.isFirstMessage {
            profileImageView.setImage(url: (sender.object(forKey: "picture") as? PFFile)?.url, fallbackText: presentable.username)
        } else {
            PFUser.query()?.whereKey("objectId", equalTo: presentable.message.senderUserId).getFirstObjectInBackground { [weak self] user, error in
                self?.profileImageView.setImage(url: (user?.object(forKey: "picture") as? PFFile)?.url, fallbackText: presentable.username)
            }
        }
    }

    // MARK: Reuse -

    override func prepareForReuse() {
        super.prepareForReuse()

        profileImageView.kf.cancelDownloadTask()
        profileImageView.image = nil
    }

}

在我的 View Controller 中:

let cell = tableView.dequeueReusableCell(withIdentifier: "MessageCell") as! MessageCell
let presentable = CellPresentable(for: message, isFirstMessage: isFirstMessage, isLastMessage: isLastMessage)
cell.configure(with: presentable)

return cell

Answer 1

在 MessageCell 的配置函数中尝试以下代码

profileImageView.image = nil

新的函数代码:

func configure(with presentable: CellPresentable) {
    self.presentable = presentable
    profileImageView.image = nil
    if let sender = presentable.sender, presentable.isFirstMessage {
        profileImageView.setImage(url: (sender.object(forKey: "picture") as? PFFile)?.url, fallbackText: presentable.username)
    } else {
        PFUser.query()?.whereKey("objectId", equalTo: presentable.message.senderUserId).getFirstObjectInBackground { [weak self] user, error in
            self?.profileImageView.setImage(url: (user?.object(forKey: "picture") as? PFFile)?.url, fallbackText: presentable.username)
        }
    }
}