Question

我收到一个未提交的CATransaction警告，我无法解决问题。我的应用程序工作得很好它正在做我期望的每件事，屏幕更新标签我想要的速度，它看起来都很好。

    Dec 10 10:40:10 my-iPhone myAppName[5967] <Warning>: CoreAnimation: warning, deleted thread with uncommitted CATransaction; set CA_DEBUG_TRANSACTIONS=1 in environment to log backtraces.

我设置了CA_DEBUG_TRANSACTIONS = 1并找到了以下列表。

    Dec 10 10:43:45 my-iPhone myAppName[5994] <Warning>: CoreAnimation: warning, deleted thread with uncommitted CATransaction; created by:
    0   QuartzCore                          0x348fc65d <redacted> + 220
    1   QuartzCore                          0x348fc541 <redacted> + 224
    2   QuartzCore                          0x348fc325 <redacted> + 24
    3   QuartzCore                          0x34900489 <redacted> + 44
    4   QuartzCore                          0x34905091 <redacted> + 456
    5   QuartzCore                          0x34904ebf <redacted> + 42
    6   QuartzCore                          0x34904e91 <redacted> + 44
    7   myAppName                       0x000d9ec1 -[MainViewController updateProgress:] + 56
    8   Foundation                          0x3a75067d <redacted> + 972
    9   libsystem_c.dylib                   0x397d6311 <redacted> + 308
    10  libsystem_c.dylib                   0x397d61d8 thread_start + 8

导致此警告的代码如下所示：

   - (void)updateProgress:(NSString*) myLabelString
    {
    //this is updating a UILabel on the main view
    [myLabel setText:myLabelString];

    }

从for循环调用它，我调用performSelectorinBackground：

for (;;) {
   // Do stuff here to set up the info for the string

    [self performSelectorInBackground:@selector(updateProgress:) withObject:myLabelString];
    usleep(100000);
    if (stopLoop == YES) {
    // do stuff before we exit for loop            
        break;
    }

}

我已经尝试了几个主要的想法，确保在退出选择器“updateProgress”之前确保对myLable的更新已完成，唯一的作用是将时间（+56）更改为更大的数字。我也尝试过使用：

    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:1.0f];    
    // edit UILabel here    
    [UIView commitAnimations];

我从另一篇文章中尝试了这个，但由于我没有使用核心动画，因此编译器反对“CATransaction”作为未声明的标识符，我并不感到惊讶。

      [CATransaction begin];
      [CATransaction setDisableActions:YES];
      //
      [CATransaction commit];

有关如何确定标签更新是否完整的任何建议？正如我所说的应用程序正在运行，我只需要清除此警告。

Answer 1

此问题已在开发者论坛上得到解答。事实证明我在后台线程上做UIKit工作。

我换了一行：

    [self performSelectorInBackground:@selector(updateProgress:) withObject:myLabelString];

要：

    [self performSelectorOnMainThread:@selector(updateProgress:) withObject:myLabelString waitUntilDone:NO];

我尝试将WaitUntilDone设置为YES，这也有效。

Answer 2

确保在主线程上进行任何UI绘制的另一种方法，如Stephen所描述，使用函数dispatch_async()

// Perform all drawing/UI updates on the main thread.
dispatch_async(dispatch_get_main_queue(), ^{
    // Perform any drawing/UI updates here.
});

有关dispatch_async()和performSelectorOnMainThread:withObjects:waitUntilDone:之间差异的相关帖子，请参阅Whats the difference between performSelectorOnMainThread and dispatch_async on main queue?

iOS 6：CoreAnimation：警告，已删除的线程与未提交的CATransaction

2 个答案: