How to debug a program on iPhone IOS xcode4 suddenly crashes and no code can be found

Xcode4 settings are not the same: find arguments in edit-> Scheme (in xcode 4.2, choose product-> edit Scheme)

Set the following three values to yes.

NtutoreleasefreedobjectCheckenabled

Nszombieenabled

Nsdebugenabled

Also reprinted 2 debugging exc_bad_access good article http://blog.zol.com.cn/2387/article_2386505.html
Http://www.cnblogs.com/likwo/archive/2011/02/28/1967066.html

This is also true for foreigners: I had similar issue; turns out I was
Not retaining a uibutton properly. how I found the cause: -Enable zombies-run the project with 'location' instruments-use the app to trigger the bug-check that instruments show message 'zombie messaged' on the timeline-There shocould be a link that
Opens calayer details: when it was allocated and deallocated-you are interested in the place where is was allocated, shocould be that aha !!! Place in your code


I use zombies on the simulator, and then run the program. When the program crashes, there will be a crash point and code.
To another article:

Method 1:

Paeholdtranmaincontrol * control = [[paeholdtranmaincontrol alloc] init];

[Self. navigationcontroller pushviewcontroller: Control animated: Yes];

[Control release];

Alloc has a control and release, and the running will crash. No prompt is displayed. Only exc_bad_access is displayed on the console.

Use the nszombieenabled parameter and the mallocstacklogging parameter to display-[calayer release]: Message sent to deallocated instance 0x13570810

After a long time, I used the following methods to locate the problem:

Open Instrument --> IOS simulator:

Select All -- "zombies to run. When disconnected, view the stack trace to track

 

Method 2: for example, the output in the console is as follows:

Testapp [1472: 207] ***-[nsobject release]: Message sent to deallocated instance 0x6019170

In the GDB Console, run shell malloc_history <pid> <mem_address>

PID = process ID (e.g. 1472)

Mem_address = memory address of instance (e.g. 0x6019170)

The call stack is displayed.