我如何在@ try / @ catch块中崩溃？ [英] How did I crash in a @try/@catch block?

问题描述

我收到以下崩溃报告（截断）

 异常类型：EXC_CRASH（SIGSEGV）
异常代码： 0x00000000，0x00000000 
崩溃线程：0 
 
线程0名称：调度队列：com.apple.main线程
线程0崩溃：
 0 libsystem_kernel.dylib 0x36df00d8 __psynch_mutexwait + 24 
 1 libsystem_c.dylib 0x31760674 pthread_mutex_lock + 376 
 2 CoreFoundation 0x31f2338a CFRunLoopWakeUp + 50 
 3 WebCore 0x308d0bc8 _WebThreadRun + 284 
 4 UIKit 0x37921c7a  -  [UIWebDocumentView _runLoadBlock：] + 38 
 5 UIKit 0x37921c3a  -  [UIWebDocumentView _cleanUpFrameStateAndLoad：] + 114 
 6 UIKit 0x37921bbe  -  [UIWebDocumentView loadHTMLString：baseURL：] + 78 
  

关注的是调用代码如下所示：

  @try {
 [webView loadHTMLString：htmlString baseURL：nil]; 
 [webView setNeedsDisplay]; 
} 
 @catch（NSException * exception）{...} 
  

那么，我是如何设法从一个异常处理程序中抛出一个异常？

我没有从catch中调用throw方法。所有我在做的是转储到NSLog的异常，webView和htmlString。如果他们导致异常，我会期望崩溃堆栈看起来有所不同。

这是否似乎减少到潜在的操作系统错误？

解决方案

这是一个细分错误（SIGSEGV），不是例外。 b
$ b

这些错误不是例外，这意味着你不能使用try / catch块。

分段错误意味着你是尝试访问不属于您的应用程序的内存区域。

在您的情况下，可能是自动释放的对象被释放，然后访问（指针不再有效，因为对象被释放）

确保你的 htmlString 变量仍然指向到一个有效的对象...

顺便说一句，我不认为在使用后需要调用 setNeedsDisplay loadHTMLString 。

I received the following crash report (truncated)

Exception Type:  EXC_CRASH (SIGSEGV)
Exception Codes: 0x00000000, 0x00000000
Crashed Thread:  0

Thread 0 name:  Dispatch queue: com.apple.main-thread
Thread 0 Crashed:
0   libsystem_kernel.dylib          0x36df00d8 __psynch_mutexwait + 24
1   libsystem_c.dylib               0x31760674 pthread_mutex_lock + 376
2   CoreFoundation                  0x31f2338a CFRunLoopWakeUp + 50
3   WebCore                         0x308d0bc8 _WebThreadRun + 284
4   UIKit                           0x37921c7a -[UIWebDocumentView _runLoadBlock:] + 38
5   UIKit                           0x37921c3a -[UIWebDocumentView _cleanUpFrameStateAndLoad:] + 114
6   UIKit                           0x37921bbe -[UIWebDocumentView loadHTMLString:baseURL:] + 78

The concern is that the calling code looks like this:

@try {
    [webView loadHTMLString:htmlString baseURL:nil];
    [webView setNeedsDisplay];     
}
@catch (NSException *exception) {...}

So, how did I manage to throw an exception from within an exception handler?

I didn't call the throwing method from inside catch. All I'm doing there is dumping to NSLog the exception, the webView, and the htmlString. If they were causing the exception I would expect the crash stack to look differently.

Does this seem to reduce into a potential OS bug?

解决方案

This is a segmentation fault (SIGSEGV), not an exception.

Those faults aren't exceptions, meaning you can't use a try/catch block.

A segmentation fault means you are trying to access a memory region that doesn't belong to your app.

In your case, it may be cause be auto-released objects that gets deallocated, and then accessed (the pointer is not valid anymore, since the object was deallocated).

Ensure your htmlString variable is still pointing to a valid object...

By the way, I don't think calling setNeedsDisplay is needed after using loadHTMLString.

这篇关于我如何在@ try / @ catch块中崩溃？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！