在 iOS 11 之前，我们使用：
func tableView(_ tableView: UITableView, editActionsForRowAt indexPath: IndexPath) -> [UITableViewRowAction]?
来对 Cell 的滑动手势出现的按钮进行自定义。
如下图：

    func tableView(_ tableView: UITableView, editActionsForRowAt indexPath: IndexPath) -> [UITableViewRowAction]? {
        
        let deleteAction = UITableViewRowAction(style: .destructive, title: "删除") { (action, indexPath) in
            self.titles.remove(at: indexPath.row)
            tableView.deleteRows(at: [indexPath], with: .left)
        }
        
        let archiveAction = UITableViewRowAction(style: .normal, title: "归档") { (action, indexPath) in
            
        }
        
        return [deleteAction, archiveAction]
    }

而在 iOS 11 之前，非常希望能实现系统那样直接一滑到底删除某个 Cell 的效果。
现在，从 iOS 11 开始提供了新的代理方法，并且在未来将要取代
func tableView(_ tableView: UITableView, editActionsForRowAt indexPath: IndexPath) -> [UITableViewRowAction]?
这个用了很久的方法。

新的方法提供了：左侧按钮自定义、右侧按钮自定义、自定义图片、背景颜色，通过 UIContextualAction 来设置。

    // 左侧按钮自定义
    func tableView(_ tableView: UITableView, leadingSwipeActionsConfigurationForRowAt indexPath: IndexPath) -> UISwipeActionsConfiguration? {
        
        let leftAction = UIContextualAction(style: .normal, title: "左侧") { (action, view, finished) in
            
            finished(true)
        }
        
        
        return UISwipeActionsConfiguration(actions: [leftAction])
    }
    
    // 右侧按钮自定义
    func tableView(_ tableView: UITableView, trailingSwipeActionsConfigurationForRowAt indexPath: IndexPath) -> UISwipeActionsConfiguration? {
        
        let deleteAction = UIContextualAction(style: .destructive, title: "删除") { (action, view, finished) in
            
            self.titles.remove(at: indexPath.row)
            tableView.deleteRows(at: [indexPath], with: .automatic)

            // 回调告知执行成功，否则不会删除此行！！！
            finished(true)
        }
        
        
        let archiveAction = UIContextualAction(style: .normal, title: "归档") { (action, view, finished) in
            
        }
        
        
        return UISwipeActionsConfiguration(actions: [deleteAction, archiveAction])
    }

Objective-C

- (nullable UISwipeActionsConfiguration *)tableView:(UITableView *)tableView trailingSwipeActionsConfigurationForRowAtIndexPath:(NSIndexPath *)indexPath {
    
    UIContextualAction *deleteAction = [UIContextualAction
                                        contextualActionWithStyle:UIContextualActionStyleDestructive
                                        title:@"删除"
                                        handler:^(UIContextualAction * _Nonnull action,
                                                  __kindof UIView * _Nonnull sourceView,
                                                  void (^ _Nonnull completionHandler)(BOOL))
    {
        [self.titles removeObjectAtIndex:indexPath.row];
        
        [self.tableView deleteRowsAtIndexPaths: [NSArray arrayWithObjects:indexPath, nil] withRowAnimation:UITableViewRowAnimationAutomatic];
        
        completionHandler(true);
    }];
    
    // 设置按钮图片
    [deleteAction setImage:[UIImage imageNamed:@"Star"]];
    
    
    NSArray *actions = [[NSArray alloc] initWithObjects:deleteAction, nil];
    
    return [UISwipeActionsConfiguration configurationWithActions:actions];
}