iOS:Tableview 开始更新从不播放动画 [英] iOS: Tableview Begin updates never plays animation

问题描述

当用户长按一个单元格并确认更改时，我编写了一些代码来从后端和本地数据存储中删除帖子.但是，tableview 不会更新.我断点了我的代码并且执行了 tableView 操作代码，为什么我的行没有从视图中删除?

I have written some code to delete a post from the back end and local data storage when a user long presses a cell and confirms the change. However the tableview does not update. I have breakpointed my code and the tableView manipulation code is executed, why is my row not being removed from the view?

let alertView = UIAlertController(title: "Really?", message: "Are you sure you want to delete this post? Once you do it will be gone forever.", preferredStyle: .Alert)
    alertView.addAction(UIAlertAction(title: "Delete Post", style: UIAlertActionStyle.Default, handler: { (alertView:UIAlertAction!) -> Void in
        let p = post.getRawPost()
        p.deleteInBackgroundWithBlock({ (deleted:Bool, error:NSError?) -> Void in
            // Remove from the local datastore too
            p.fetchFromLocalDatastore()
            p.deleteInBackgroundWithBlock({ (deleted:Bool, error:NSError?) -> Void in
                // Update the table view
                self.tableView.beginUpdates()
                self.tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Left)
                self.tableView.endUpdates()
        })

    })
}))

据我所知，beginUpdates 和 endUpdates 用于更新 tableView 的特定部分，而无需执行完整的 reloadData 调用来源.我在这里遗漏了什么吗?

As I understand it, beginUpdates and endUpdates is used to update specific sections of a tableView without needing to perform a full reloadData call on the source. Am I missing something here?

UPDATE 我将 tableView 更新代码移动到主线程，每当调用 endUpdates 时都会导致崩溃.我的新代码如下所示，并在主线程上调用:

UPDATE I moved the tableView update code to the main thread, this produced a crash whenever endUpdates is called. My new code looks as below, and is called on the main thread:

self.tableView.beginUpdates()
self.tableView.deleteRowsAtIndexPaths([NSIndexPath(forRow: indexPath.row, inSection: indexPath.section)], withRowAnimation: UITableViewRowAnimation.Automatic)
self.tableView.endUpdates()

推荐答案

将下面的代码片段包裹在 MAIN THREAD 中:

Wrap the code snippet below in MAIN THREAD instead:

self.tableView.beginUpdates()
self.tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Left)
self.tableView.endUpdates()

<小时>

编辑崩溃

p.deleteInBackgroundWithBlock({ (deleted:Bool, error:NSError?) -> Void in
   // Remove from the local datastore too
   p.fetchFromLocalDatastore()

   // Delete the desired item from array
   ...
   // Remove cell that the item belong to animated in main thread
   dispatch_async(dispatch_get_main_queue(), {
       // Update the table view
       self.tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Left)
   })
})

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