I'm getting the following Exception on iOS6 (on an App with CoreData):
"2012-10-15 10:21:28.952 MyApp[68650:c07] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '* -[__NSArrayM insertObject:atIndex:]: object cannot be nil'
* First throw call stack:
(0x28e6012 0x2659e7e 0x2899b6a 0x2899a20 0x1646941 0x1642c67 0x164f846 0x164f908 0x6c540 0x2057e83 0x28a5376 0x28a4e06 0x288ca82 0x288bf44 0x288be1b 0x33967e3 0x3396668 0x15a165c 0x13a22 0x2845)
libc++abi.dylib: terminate called throwing an exception"
This doesn't happen on iOS5, so something happens on iOS6 what I don't understand.
I set a Breakpoint on every point where I call insertObject:atIndex: but these are not called - it have to be something in this libc++abi.dylib which gets called and crashes.
Does anyone know what could be wrong?
thank you
This is probably because either iOS5 did not throw an exception for this error (and should have, but now iOS6 throws one which is better than having erratic behavior later), or because you have some different behavior in iOS6 which makes your object nil whereas it was not in iOS5.
Whatever the reason, you can add a Symbolic Breakpoint on the insertObject:atIndex: symbol, so that it will break every time this method is called, wherever it is in your application (in your own code or not).
Go to the "Breakpoints Navigator" view (Cmd-6 shortcut)
Click on the "+" button to add a symbolic breakpoint
Set the symbolic breakpoint to break when it hits the symbol [NSArray insertObject:atIndex:]
Thus you can see when this is called with a nil value for the first parameter and fix your problem where it occurs.
You can also instead add an Exception Breakpoint to break when an exception is thrown, thus knowing when in the code your exception occurs. This is another way to let you know which part of the code (your own or another) generate the exception.
Once the breakpoint has been hit and the program stops before the exception occurs, you can check in the call stack what part of your own code led to trigger this exception at the end.
The reason for the crash is that the object you are trying to insert is nil. This means it is not properly instantiated. This in turn means something has gone awry before you reached that exception.
Could you post the code that alloced and initialized the object you were trying to insert?
In order to find the relevant line of code, please try the following: Go to the "Exception" tab in your Xcode project:
Then click the "+" button (at the bottom of the page) and select "Add Exception Breakppoint ...". Leave all settings to their defaults and click "Done".
If you rerun your project it should now stop at the relevant line of code before the exception is thrown. Then you can move up the call-stack and identify from where in your code you called the library function that is responsible for this behavior. Then try to see if all objects are correctly initialized at this point.
Related
In my Xcode project i added an exception breakpoint to stop on throw. Since i got some problems with a -[__NSCFNumber length]: unrecognized selector sent to instance. But my code still stops at
int retVal = UIApplicationMain(argc, argv, nil, nil);
I know that it means that somewhere in my code I'm setting a int value to a NSString, but i really don't know where that is, which means I'm getting nowhere. Cant find the root to the exception and i got so many lines of code that i can't link it here.
So anyone know another way to make Xcode break where the problem is and not break on the main.m's UIApplicationMainthe?
Thanks a lot for your time.
EDIT: heres where my thread breaks
And this is where the exception breakpoint stops the code
My call stack looks like this:
Without code we can not able to help you but This error saying that your are measure length of NSNumber instead of NSString. Check it step by step (by using break point) where you are doing mistake such like that, just sear on google there are so may answers.
Here are the steps.
Move to "Breakpoint Navigator".
Click + symbol at bottom-left corner of navigator.
You should see this :
click on Add Exception Breakpoint
click on Done
and you click on done and after you run your porgramme and it will break where the problem is.
So I keep getting this crash and break in my code, but I can't figure out exactly where it's coming from. Xcode doesn't break on the line that is relevant to this, and I looked through all of the thread stacks and none of them show the break. Here is what I am getting:
*** Terminating app due to uncaught exception 'NSGenericException', reason: '***
Collection <CALayerArray: 0x17746b10> was mutated while being enumerated.'
My question is, how so I find out where this array is? Is there some way to look it up in the Xcode console by address to point me to what exactly is happening here? I can't find where I would be mutating some array just by eyeballing my code.
Add exception breakpoint and check the location for crash.
1) Go to the breakpoint navigator.
2) At the bottom left corner click on the ADD
3) Now select "Add Exception Bearkpoint" in that.
4) Make sure "Exception Breakpoint" is enabled.
5) Right click on breakpoint and Change the exception type to Objective-C.
Now run you app and debug the crash area.
SUMMARY
When I set an exception breakpoint, I don't get the exception message. How do I get the exception message? I already know how to get the stack trace, but that doesn't include the exception message.
DETAILS
In the past I developed iOS Apps with Xcode and when there was a problem, I'd get an error/exception. The exception would often have a message like "can't dereference null" or whatever.
Now, using Xcode 4.6.x for the past several weeks I've never gotten an exception message. I'll often get a SIGABRT. I put in the break on exception breakpoint and it will break there, but it's off in some assembly within the iOS SDK and I never get a message.
In fact, I can't remember the last time I saw anything show up in the debugger console.
Did exception info dissappear with the migration to LLVM?
It's very frustrating to have my app just crash in the SDK without knowing why. I check the last function to make sure things are set up correctly (objects allocated, etc) and they are which means I'm left with no clues.
Is it possibly a build setting held over from the past is somehow turning off exception messages?
Please reopen question. It now has an answer!
In the comments an excellent answer has been given. This should be promoted to full answer, and so I can mark the question answered and others who have this common issue can find it. In order for that to happen, the question needs to be reopened! (I'll delete this plea after that happens.)
I will update Jeff's answer here:
To have both the line causing the exception highlighted (and not UIApplicationMain() in main.m) AND to see the reason for the exception (e.g., "error: A fetch request must have an entity."), do this:
In the Breakpoint navigator:
Add (+), Add Exception Breakpoint
Select the new breakpoint, Control-Click, Edit Breakpoint
Add Action
Enter: po $arg1
The relevant part of the stack trace will be in the nagivator area.
This seems to still work in Xcode 9
Here is my addition for use with Xcode 6 and below.
Enter: po (NSException*) $eax
In Xcode 6 you must explicitly provide the object type because it is no longer inferred.
For Xcode 7-9 (based off Jeff's answer):
In the Breakpoint navigator:
Add (+), Add Exception Breakpoint
Select the new breakpoint, Control-Click, Edit Breakpoint
Add Action
Enter: po $arg1
To have both the line causing the exception highlighted (and not UIApplicationMain() in main.m) AND to see the reason for the exception (e.g., "error: A fetch request must have an entity."), do this:
In the Breakpoint navigator:
Add (+), Add Exception Breakpoint
Select the new breakpoint, Contorl-Click, Edit Breakpoint
Add Action
Enter: po $eax
The relevant part of the stack trace will be in the nagivator area.
Yes xcode is not so friendly for debugging. I like this article which helps me to understand crash logs a bit clearly))
Demystifying iOS Application Crash Logs
Also do this if you see error "message sent to deallocated instance"
'Products -> Edit Scheme -> Enable Zombie Objects'
this will enable zombie objects and when you do profile to your project choose
"zombie", cause error and you will be able to see which objects was deallocated e.g NSArray *myArray
The information I get from po $eax or po (NSException *)$eax seems to be different from what Xcode would print if no exception breakpoints are set. So I do the following,
Add an exception breakpoint
Exception occurs, breakpoint was hit -> I know the location
Temporarily disable breakpoints (second button on the left in Debug area)
Continue program execution (third button on the left in Debug area)
Details are printed -> I know the cause
Obviously not very elegant and flexible, but at least I two big questions are answered (where and why).
You can use bt or thread backtrace command to print error trace
Show the stack backtrace for the current thread.
The same stack trace you can find in crash reports
Information about current thread use currentThread
//Objective-C
po [NSThread currentThread]
//Swift
po Thread.currentThread
*Sometimes you can use fr v(or just v from XCode 10.2) when po is not working
I'm trying to get better at using Xcode. I have the AllExceptions break point turned on. When my app crashes, I see this:
*** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 1 beyond bounds [0 .. 0]'
*** First throw call stack:
(0xbb8052 0x209cd0a 0xba4db8 0x2255f2 0xc2439 0x12a5e0f 0x12a6589 0x146bfb1 0x147617c 0x12938e1 0x1290602 0x129b211 0x129b23f 0xc16a6 0x138a4c 0x138852 0x14d0e39 0x14d0143 0x14d13cf 0x14d3a31 0x14d398c 0x14cc3e7 0x1234812 0x1234ba2 0x121b384 0x120eaa9 0x28d3fa9 0xb8c1c5 0xaf1022 0xaef90a 0xaeedb4 0xaeeccb 0x28d2879 0x28d293e 0x120ca9b 0x265c 0x25c5)
terminate called throwing an exception(lldb)
On the LHS, when I look at the different threads, I don't see anything that really makes sense. I see some CFRunLoop stuff, but I don't see any "normal" method names like UITableView delegate/datasource methods or my own methods. I was wondering if there was a more informative stack trace available instead of the hex stuff when my app crashes. I know I can set breakpoints at each place I'm accessing the array I think I have a problem with since I'm basically just trying to have an accordion-like tableview with our specific datasource, but I was wondering if there was a faster way by looking at something useful in Xcode. Thanks!
In Xcode,
go to Breakpoint navigator on the left pane.
Click '+' at the bottom.
Choose 'Add exception Breakpoint...'
Let the default selections there and click 'Done'.
Rerun the app and see if execution stops at the line which causing this exception.
The easiest way to handle the exceptions in XCode during development is to add the exception break points.
You can do that as following.
From left menu select Exceptions navigator
Add the exception break point from bottom left button.
Add break point for all the exceptions
Run the app.
In most of the cases XCode will stop the execution on exception and point at the line that caused the exception.
After upgrading to XCode4 (v. 4.2, 4D199) it seems every time my apps crash while debugging, the debugging points to main(), and the stack is unsymbolicated and useless.
This has been working fine for years, I have no idea what has gone wrong.
I'm using GDB. I also tried the LLDB as per this advice, and it didn't work either (similar, useless stack).
My breakpoints work, I get the full stack, and can inspect variables when my code hits those.
Steps to reproduce:
NB. this happens with my own project, but I'll use Apple's code here to remove that variable from the equation
Download the following sample from Apple: https://developer.apple.com/library/ios/#samplecode/UICatalog/Introduction/Intro.html#//apple_ref/doc/uid/DTS40007710
In the ImagesViewController class, add the following code to the viewDidLoad method (so it will crash – we want it to crash for this test):
// please note: this code is designed to crash! I want it to crash, to highlight my issue with XCode.
NSMutableArray* test = [NSMutableArray new];
[test insertObject:NULL atIndex:0];
Then run the app & hit the 'Images' row.
It crashes with a message like:
2011-12-23 14:07:02.788 UICatalog[13394:707] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[__NSArrayM insertObject:atIndex:]: object cannot be nil'
*** First throw call stack:
(0x37bbb8bf 0x316a11e5 0x37b1020f 0x699f 0x34fac7ff 0x34fb8c39 0x34fb8aa9 0x34fb898f 0x34fb815b 0x34fb7f53 0x34fac673 0x34fac349 0x66c1 0x35026565 0x3509ece7 0x31aec943 0x37b8fa63 0x37b8f6c9 0x37b8e29f 0x37b114dd 0x37b113a5 0x3768ffcd 0x34fa1743 0x2459 0x2418)
terminate called throwing an exception(gdb)
View in xcode:
Thanks to brigadir for pointing me to the solution!
It works well. Here's some screenshots for how to solve this for anyone finding my question:
Tap the plus button of the breakpoints tab
Then click Done