I am using Crashlytics to track and fix crashes in my live app. However, I am not very knowledgeable on how to understand what the thread is telling me.
Usually on XCode, you get specific information regarding the error (such as, "unexpectedly found nil", etc.). Is there such information in a Crashlytics Dashboard? If not, how can I understand better what is causing the crash in the app?
Here is a picture of an example crash.
Thanks!
You error is inside cellForRowAtIndexPath. If I'm not mistaken, The blue labels are methods inside your classes.
And they work like a bread crumbs trail for all the processes that happened until the crash. 0 is the first interaction where N is the last method triggered before your app crashed.
But you must agreed with me that your problem probably isn't inside UIKit or Foundation methods, right?
Is that helpful?
If not, feel free to contact their support, they are really responsive!
Here is they're email: support#fabric.io
I'm trying to debug an EXC_BAD_ACCESS crash using NSZombie. My app creates lots of large objects though and with NSZombie enabled they aren't getting released causing the app to crash in seconds. This means I can't even cause the EXC_BAD_ACCESS crash before the app crashes due to low memory.
Is there an alternative? Can I enable NSZombie on specific file instead of the entire project? How else could I debug this crash (I know it's caused by UIGestureRecognizer but I use them a lot so it doesn't narrow down the issue significantly).
Thanks.
Edit:
Thanks for the advice. I think I may have solved the issue and will report back after more testing.
Edit 2: Sovled the issue myself but selected the answer which seems like it would be a good solution to any similar issues in the future.
All I can think of is implementing it manually; create a proxy container that holds an object of type id and nominates that as -forwardingTargetForSelector: as well as getting it to respond to -isKindOfClass:, etc.
Disable ARC for the proxy and have it retain itself during init and check its own retainCount when nominating a forwarding target.
If the count is 1 then raise an exception or log a warning or whatever.
Have suspect classes wrap themselves in and return a proxy as the last line of their unit.
For possible bonus points, store [NSThread callStackSymbols] somewhere (probably on disk) during the proxy's unit so you can at least find out where the incorrectly managed object was created.
NSZombies was/is for apps that use their own memory management. If your app uses ARC then this won't help.
Create a new Breakpoint: All Exceptions
That should usually show you where you trigger the bad access.
Testing my app which gets location data from an api and displays in a table view. Was testing something else today and app crashed - EXC_BAD_ACCESS (code=1, address=0X0). What does this mean and how do I read the information provided by Xcode to figure out how to fix?
EXEC_BAD_ACCESS usually means that you are trying to access an object which is not in memory or probably not properly initialized.
Check in your code,
if you are accessing your Dictionary variable after it is somehow removed?
is your variable properly initialized? You might have declared the variable but did not initialize it and accessing it.
There could be a ton of reasons and cant say much without seeing any code.
Try to turn on NSZombieOjects - this might provide you more debug information. Refer to here How to enable NSZombie in Xcode?
IF you would like to know where and when exactly is the error occurring, you could check for memory leaks using instruments. This might be helpful http://www.raywenderlich.com/2696/instruments-tutorial-for-ios-how-to-debug-memory-leaks
Based on the information you provided. My guess is that the library is calling out to a block you provided. Inside that block is a Dictionary which has something wrong with it.
Good luck!
I'm working on an iPad application and a recent change I made is causing the app to die with "signal SIGTRAP". The stack trace doesn't help and I can't pinpoint what part of the code is causing this to happen (but I do know which function it starts from).
Without going into details about the application I was wondering if there are some general tips for debugging this kind of thing (SIGTRAP)?
I've managed to narrow down which function call causes this to happen. The weird thing is that if I break and step into the function then it works fine. But if I let it run without a breakpoint then it crashes.
The function calls a bunch of other things which also involve asynchronous network connections. I put logs all over my code and all my logs print fine, so it seems something "under the hood" is causing this failure. I'm also using a 3rd party framework which may be causing this issue?
Is this even a code-related issue? I read somewhere that SIGTRAP is a debugger thing.
What causes this kind of crash and where should I be focusing my efforts to fix it?
Any help you can provide is greatly appreciated.
Thanks!
Having a hard time tracking down a crash in an iPad application. The difficulty really stems from the fact that there is no errors or stack trace present when the application fails. It simply goes away like Keiser Soze, "And like that, poof. He's gone.".
I've replicated the crash on both the simulator and the device. There are zero device logs, nothing in the console, etc.
I know that during the crash some CoreGraphics operations are occurring in a background thread. Typically, three or so NSOperations are kicking of some image blends.
The blending consists of CGContext* calls (DrawImage, SetBlendMode, SetAlpha, etc). The NSOperation calls back to a delegate in the main thread to handle the image and set it to UIImage, so it shouldn't be a UI main thread conflict, but I'm not discounting anything at this point.
Are there some Xcode tricks I'm missing to track down exactly what is happening? Or at least get a better hint of where the problem lies?
EDIT I have run the app in Instruments tracking memory usage and see that it is pretty rock steady around 2MB. So, don't think it's a memory issue. But after consideration, this rock steady 2MB seems abnormally low. Is there a chance Instruments is not picking up the CoreGraphics allocations?
Try reading the registers.
Whenever my app crashes without error, in most cases I have found the exception in the registers.
First go to Exceptions tab and 'Add Exception Breakpoint' using the + at the bottom left corner.
Then when the app crashes click on "0 objc_exception_throw" under Thread 1
Finally in the console enter:
register read
(you should get a list of registers)
po $rax (normally the exception is in 'rax')
(you should see the exception output on the console)
Hope this helps.
For lack of a better solution, and if it isn't obvious, pepper your app with NSLogs to circle where this occurs, then drill deeper from there via breakpoints and/or additional logs.
Super late answer, but I've found that using try/catch helps give information when I can't get a stack trace and my application pulls a Keiser Soze.
#try
{
// suspected code causing crash/errors
}
#catch (NSException *exception)
{
NSLog(#"Exception: %#", exception);
}
In my case, it was because of bad outlet connection in the storyboard.
Check using breakpoint if viewDidLoad method of UIViewController to be loaded gets called. If not, check your outlet connections in the storyboard.
Incorrect connection crashes the app without any error or stack trace.
I am wondering what happened to the this class is not key value coding-compliant for the key error that used to show in older versions of XCode.
In my case, it was because I had "Zombie Objects" enabled in the scheme to help find the problem, which was eventually causing it to run out of memory and crash.
In my case it was due to an object being released. Normally it would say message sent to deallocated instance or something like that, but it didn't. I checked the iPhone's logs and found this: KERN_INVALID_ADDRESS, which I googled and came across this: KERN_INVALID_ADDRESS
Enabled zombie objects and found that I tried to use a deallocated instance. It also told me what object it was in the logs afterwards.
Hope it helps for future visitors.