表视图单元格中带有 UIImageView 的 UITapGestureRecognizer 不工作 Swift

Question

在我的表视图控制器中，我从后端请求数据。然后将数据添加到一个数组中，并为请求中的每一行提供一个视图模型。

let getNotifications = GETNotificationsByUserID(user_id: user_id)
getNotifications.getNotifications { notifications in
    self.notifications = notifications.map { notification in
    let ret = NotificationViewModel()
    ret.mainNotification = notification
    return ret
}

class NotificationViewModel {
    var mainNotification: Notifications? {}
}

struct Notifications: Codable {
    var supporter_picture:String?
}

在同一个表视图控制器中，然后我将数组中的每个项目添加到表视图单元格中的变量中。

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "MyCell", for: indexPath as IndexPath) as! NotificationCell
    cell.user_image.isUserInteractionEnabled = true
    let item = self.notifications[indexPath.item]
    cell.viewModel = item
    return cell
}

从我的表格视图单元格变量的数据中下载图像并设置我的 UIImageView 图像。

UITableViewCell

class NotificationCell: UITableViewCell {
    var viewModel: NotificationViewModel? {
        didSet {
            if let item = viewModel {
                self.username.text = item.mainNotification?.supporter_username
                item.supporterImageDownloader = DownloadImage()
                item.supporterImageDownloader?.imageDidSet = { [weak self] image in
                    self?.user_image.image = image
                }
                if let picture = item.mainNotification?.supporter_picture {
                    item.supporterImageDownloader?.downloadImage(urlString: picture)
                } else {
                    self.user_image.image = UIImage(named: "profile-placeholder-user")
                }
            }
        }
    }
}

UIImageView 是从惰性闭包变量创建的。惰性闭包变量还包含一个 UITapGestureRecognizer。

UITableViewCell

lazy var user_image: UIImageView = {
    let image = UIImageView()
    let gesture = UITapGestureRecognizer()
    gesture.addTarget(self, action: #selector(userImageClicked(_:)))
    gesture.numberOfTapsRequired = 1
    gesture.numberOfTouchesRequired = 1
    image.addGestureRecognizer(gesture)
    image.isUserInteractionEnabled = true
    return image
}()
   
override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
    super.init(style: style, reuseIdentifier: reuseIdentifier)
    self.isUserInteractionEnabled = true
    addSubview(user_image)
    user_imageContraints()
}
    
func user_imageContraints() {
    user_image.translatesAutoresizingMaskIntoConstraints = false
    user_image.topAnchor.constraint(equalTo:topAnchor, constant: 8).isActive = true
    user_image.leadingAnchor.constraint(equalTo:leadingAnchor, constant: 8).isActive = true
    user_image.heightAnchor.constraint(equalToConstant: 40).isActive = true
    user_image.widthAnchor.constraint(equalToConstant: 40).isActive = true
}

@objc func userImageClicked(_ sender: UITapGestureRecognizer) {
    print("image clicked")
}

由于某种原因，当我的 UIImageView 被点击时，它什么也没做。

Answer 1

问题出在这一行：

addSubview(user_image)

改成：

contentView.addSubview(user_image)

您绝不能将任何视图直接添加到单元格 - 只能添加到其 contentView。