“该应用程序正在从后台线程修改自动布局引擎”。 [英] "This application is modifying the autolayout engine from a background thread"

问题描述

我遇到以下错误：

此应用程序正在从后台线程修改autolayout引擎，这会导致引擎损坏每当我尝试将图像视图加载到表格视图中时，我就会发生奇怪的崩溃

This application is modifying the autolayout engine from a background thread, which can lead to engine corruption and weird crashes

相关代码如下：

whenever I try to load an image view into a table view. The relevant code is as follows:

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cellIdentifier = "ArticleCell"
    let cell = tableView.dequeueReusableCellWithIdentifier(cellIdentifier, forIndexPath: indexPath) as! ArticleCell


    let a: Article = self.articlesArray[indexPath.row] as! Article
    //let a: Article = self.newArticlesArray[indexPath.row] as! Article

    cell.titleLabel.text = a.title
    cell.descLabel.text = a.desc

    let data = NSData(contentsOfURL: a.thumbnail)
    cell.iView.image = UIImage(data: data!)

    return cell
}

func downloadArticles(){
    //JSON parsing methods here
        self.syncCompleted = true
        dispatch_async(dispatch_get_main_queue()) {
            self.tableView.reloadData()
        }
    }
    task.resume()
}

每次我点击表格中的图像时图像移动到单元格的左侧，如果我加载的图像不是UIImageView的大小，那么它会调整大小。

Every time I click the image in my table view the image moves to the left of the cell and if the image I loaded is not the size of the UIImageView then it resizes it all.

如何修复此错误？

我已经尝试过dispatch_get_main_queue代码，但它对我来说似乎没什么用。

I have tried the dispatch_get_main_queue code, but it does not seem to be doing much for me.

推荐答案

让我们确定导致自动布局引擎损坏的确切执行路径。为此，您需要将符号断点添加到以下内容：

Let's identify exact execution path which leads to auto layout engine corruption. For this you need to add symbolic breakpoint to following:

+[NSException raise:format:]

您可以这样做：

然后：

之后，一旦你的应用程序卡在断点上，请抓住并共享堆栈跟踪。您可以使用lldb控制台执行此操作：

After that once your app get stuck on the breakpoint, please grab and share the stack trace. You can do this using lldb console:

(lldb) bt
* thread #4: tid = 0x2bbc48, 0x000000010ba5ebf0 CoreFoundation`+[NSException raise:format:], queue = 'com.apple.root.default-qos', stop reason = breakpoint 1.1
  * frame #0: 0x000000010ba5ebf0 CoreFoundation`+[NSException raise:format:]
    frame #1: 0x0000000108dd5b6b Foundation`_AssertAutolayoutOnMainThreadOnly + 79
    frame #2: 0x0000000108dd5a62 Foundation`-[NSISEngine _optimizeWithoutRebuilding] + 49
    frame #3: 0x0000000108c34c0f Foundation`-[NSISEngine optimize] + 46
    frame #4: 0x0000000108c3b875 Foundation`-[NSISEngine constraintDidChangeSuchThatMarker:shouldBeReplacedByMarkerPlusDelta:] + 313
    frame #5: 0x0000000108c3b6f2 Foundation`-[NSISEngine tryToChangeConstraintSuchThatMarker:isReplacedByMarkerPlusDelta:undoHandler:] + 440
    frame #6: 0x0000000108c27715 Foundation`-[NSLayoutConstraint _tryToChangeContainerGeometryWithUndoHandler:] + 484
    frame #7: 0x0000000108c27274 Foundation`-[NSLayoutConstraint _setSymbolicConstant:constant:] + 422
    frame #8: 0x0000000108ac35d5 iosapp`ViewController.(self=0x00007fe86a6abc80) -> ()).(closure #1) + 133 at ViewController.swift:26
    frame #9: 0x0000000108ac3627 iosapp`thunk + 39 at ViewController.swift:0
    frame #10: 0x000000010c775d9d libdispatch.dylib`_dispatch_call_block_and_release + 12
    frame #11: 0x000000010c7963eb libdispatch.dylib`_dispatch_client_callout + 8
    frame #12: 0x000000010c77eb2f libdispatch.dylib`_dispatch_root_queue_drain + 1829
    frame #13: 0x000000010c77e405 libdispatch.dylib`_dispatch_worker_thread3 + 111
    frame #14: 0x000000010cad34de libsystem_pthread.dylib`_pthread_wqthread + 1129
    frame #15: 0x000000010cad1341 libsystem_pthread.dylib`start_wqthread + 13
(lldb) 

完成此操作后，我们可以确定导致问题的确切位置。

Once you've done this, we can identify exact place which causes the issue.

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