Ios 删除单元格Swift Xcode前通知控制器

我想知道如何在删除单元格之前显示删除确认（警报）。这些单元格是带有信息的字符，因此如果用户错误地删除（滑动）其中一个单元格，这将是不好的

这是允许我删除行的代码段。Im使用Xcode 10/Swift

// Delete Rows
override func tableView(_ tableView: UITableView,
               trailingSwipeActionsConfigurationForRowAt indexPath: IndexPath) -> UISwipeActionsConfiguration?
{
    let modifyAction = UIContextualAction(style: .normal, title:  "Delete", handler: { (ac:UIContextualAction, view:UIView, success:(Bool) -> Void) in
        print("Update action ...")
        success(true)

        self.namesArray.remove(at: indexPath.row)
        self.imagesArray.remove(at: indexPath.row)

        self.tableView.deleteRows(at: [indexPath], with: .fade)

    })
    modifyAction.image = UIImage(named: "delete")
    modifyAction.backgroundColor = .purple

    return UISwipeActionsConfiguration(actions: [modifyAction])

}

你可以试试

override func tableView(_ tableView: UITableView,
               trailingSwipeActionsConfigurationForRowAt indexPath: IndexPath) -> UISwipeActionsConfiguration?
{
    let modifyAction = UIContextualAction(style: .normal, title:  "Delete", handler: { (ac:UIContextualAction, view:UIView, success:(Bool) -> Void) in
        print("Update action ...")
        success(true)

         let alertView = UIAlertController(title: "", message: "Are you sure you want to delete the item ? ", preferredStyle: .alert)
         let okAction = UIAlertAction(title: "OK", style: .default, handler: { (alert) in
             self.namesArray.remove(at: indexPath.row)
             self.imagesArray.remove(at: indexPath.row)     
             self.tableView.deleteRows(at: [indexPath], with: .fade)
        })
        let cancelAction = UIAlertAction(title: "Cancel", style:.cancel, handler: { (alert) in
             print("Cancel")
        })
        alertView.addAction(okAction)
        alertView.addAction(cancelAction)
        self.present(alertView, animated: true, completion: nil)

    })
    modifyAction.image = UIImage(named: "delete")
    modifyAction.backgroundColor = .purple 
    return UISwipeActionsConfiguration(actions: [modifyAction])

}

---

您可以将显示

UIAlertController

的代码拉到一个单独的方法中，用户按delete键时可以调用该方法。下面是代码，确保闭包中包含的所有表示逻辑都被分派到主线程

func tableView(_ tableView: UITableView, trailingSwipeActionsConfigurationForRowAt indexPath: IndexPath) -> UISwipeActionsConfiguration? {
    let modifyAction = UIContextualAction(style: .normal, title:  "Delete", handler: { (ac:UIContextualAction, view:UIView, success:(Bool) -> Void) in
        DispatchQueue.main.async {
            self.showDeleteWarning(for: indexPath)
        }

        success(true)
    })

    modifyAction.image = UIImage(named: "delete")
    modifyAction.backgroundColor = .purple

    return UISwipeActionsConfiguration(actions: [modifyAction])
}

func showDeleteWarning(for indexPath: IndexPath) {
    //Create the alert controller and actions
    let alert = UIAlertController(title: "Warning Title", message: "Warning Message", preferredStyle: .alert)

    let cancelAction = UIAlertAction(title: "Cancel", style: .cancel, handler: nil)

    let deleteAction = UIAlertAction(title: "Delete", style: .destructive) { _ in
        DispatchQueue.main.async {
            self.namesArray.remove(at: indexPath.row)
            self.imagesArray.remove(at: indexPath.row)
            self.tableView.deleteRows(at: [indexPath], with: .fade)
        }
    }

    //Add the actions to the alert controller
    alert.addAction(cancelAction)
    alert.addAction(deleteAction)

    //Present the alert controller
    present(alert, animated: true, completion: nil)
}

---

只需在操作块中添加一个

UIAlertController

。不需要DispatchQueue.main.asynchy@Sh_Khan，在考虑了更多并进行了一些搜索之后，我看到人们提到，因为这些是用户发起的操作，他们相信它们将始终在主线程上被调用。你有任何书面证据吗？我明白你的意思，我也明白这是有道理的，如果苹果公司有一些明确的文档来保证这一点，那就更好了。@KyleH UIKit API在响应UI事件时总是在主队列上调用其代码。这是一个简单的事实。完美。谢谢您的时间。@AbelC没问题@rmaddy之前，苹果的委托方法中存在与用户发起的操作相关的表示逻辑问题。虽然这个雷达很旧（），但我今天仍然可以产生相同的延迟，其他人也可以产生最近的so posts/Github问题，等等。因此，您可以在我的代码中删除对主线程的调用，我只想确保您不会遇到与

didselectrowatinex

方法类似的延迟。