While debugging the program my breakpoint is not working, so please give me some advice so that it can work properly.
Maybe you've tried to use the breakpoint on unreachable code? Try setting your breakpoint somewhere before the point you want to reach and try stepping from there to see if the point is actually reached.
Possible Reasons could be.
1. After changes in the code you have not built the libraries properly so the breakpoint is not pointing to the right location in the code.
2. If you are putting a breakpoint in a library then make sure the library is build and is built in Debug mode.
3. Clean full environment and rebuild the project.
Open XCode preferences and in the Debugging tab, un-check "Load symbols lazily", this caught me out when I first started iPhone developement. Then again, it might be for any of the other reasons that people have already mentioned.
Related
Shortly after updating to Xcode 13.2.1 I started seeing some weird behaviour of breakpoints. When I run an app (in a simulator) some of my breakpoints change their look and turn to dotted blue outlined. Xcode does not stop execution at these breakpoints although code has been compiled, loaded and executed. I checked it in Console by adding some prints.
When I hover over breakpoint Xcode shows a message:
Xcode won't pause at this breakpoint because it has not been resolved
Resolving it requires that:
The line at the breakpoint is compiled.
The compiler generates debug information that is not stripped out (check the Build Settings).
The library for the breakpoint is loaded.
All trivial solutions like reloading, reapplying breakpoints have not helped.
Did anybody else see something like this? Is there a way to solve it?
Screenshot for reference:
Ok, so in my particular case rebooting laptop has helped. All breakpoints are now good. But it would still be nice to know the cause of the problem.
Make sure that the file in which you are adding breakpoint is having correct target set in target membership.
Click on .m file in which you want to add breakpoint.
Select the file inspector.
Check if you have selected correct target for that file or not (check below image).
What worked for me, was to select the files, delete them with - Delete>Move To Trash - and then drag the files back from the trash to the project.
In my case the issue was happening, because class was not added to the target, which I was trying to build.
For my case somehow the code path was never invoked and very likely considered as dead code. The same thing applies when not adding the file to the target that you want to debug.
This can be the case or somehow debugger might not be able to resolve your breakpoint. The first thing in this case should be cleaning derived data and any caches.
But instead of recloning your repo you can just delete breakpoint config from the location described in this answer
In Xcode 14 the problem is much more prevalent and "consistent". I figured out one pattern where it always fails and how to mitigate it.
If you have a final class then breakpoints set on or inside a private method will have that issue. If you remove private from the method or final from the class the breakpoints will get resolved properly.
If tried everything and nothing worked I suggest the following:
Reclone your repo
This is what worked for me.
I just passed through this problem and the solution for me was recreating the files.
Note: The ones I was trying to originally breakpoint on were copied from another project. When I created the new files, even though their Identity and Type looked just the same (target membership, encoding, paths), for some reason breakpoints started to work again.
Note 2: When copying and pasting code to your new files (if done manually), migrated breakpoints - created in the older file - will continue to fail. Only the ones created in this new file will work properly.
Hope it helps.
My case
Working on framework development. Framework is injected into the sample app for development/run purpose. Breakpoints inside the framework won't work.
Fix
Just removing xcframework in sample app and replacing with framework.
Reason
xcframework are precompiled outside of the app, so lib isn't compiled when project is built and that's why breakpoints doesn't work.
For me reboot the Xcode, and it works~
I've made an iPad App. I was able to run this App on my device and on simulator.
After I've updated several classes (which I tested in simulator) I wasn't able to run my App on my device. It gives no errors but just hangs when compiling.
I'm thinking it's something with a class which came out very large and has some mathematical functions inside (calculations of transforms etc.)
After a long runtime Xcode gives back this error (something about a 'clang error'):
Anyone has any experience with these kind of issues and could find a solution?
EDIT:
Within my viewdidload method i have set 112 float values (i.e. value = 12;) and save them (with NSUSerdefaults).
Only setting these values solved my problem. No idea why this was giving me compile errors. I'm thinking the mathematical functions (after setting the float values) took to much memory or CPU.
Did you try cleaning your build and rebuild again?
Menu > Product > Clean
close & reopen XCode, "Clean All Targets" then rebuild. It should work.
Clean your project, delete the app from you iPad and try again. Should work.
Hope it helps
Are you trying to "Build and Analyze" or an ad-hoc build or debug build?
If your code crashed because of any memory issues or bad access memory due to any infinite loop, try to enable NSZombieEnabled in your executable settings. It will point you to the code snippet where the code crashes.
To enable "NSZombieEnabled", go to
Edit Active Executables -> Arguments -> Variables in the environment -> Add name as "NSZombieEnabled" and value to "YES"
Hopes this helps.
I'm not exactly sure how to debug this but it seems that I'm getting EXEC BAD ACCESS in the main function of my app. There's no trace or logs of what's going on. I have NSZombiesEnabled but it doesn't seem to be showing anything. How would I debug this?
The first step in debugging is to find out where the crash happens. To do this you need to be able to reproduce the bug.
The Xcode debugger will usually tell you where the crash happened. It doesn't happen in main(), that's simply the entry point for the app and the top of the call stack. You can zoom in to the call stack with the slider at the bottom of the Debugger pane (in Xcode 4).
If the stack trace doesn't include any of your own code, then you may need to set an exception breakpoint in the Breakpoints pane and try again.
If all else fails, you'll have to do some digging:
1) Find a reproducible case where you can make the app crash every time (or almost every time) using the same actions.
2) Since you know what you're doing to make the app crash, you roughly know where in the code you should look. Set breakpoints at strategic places (or use NSLog). After some fishing, you'll find the exact line where the app crashed.
3) Fix the problem. :-)
It may be helpful.
Mainly you are getting this error because you have released something which is useful in furthur.So try to focus on the release.comment the line where you have used the release
Have you tried too clean and rebuild your project, and restart XCode. Latest versions of Xcode sometimes does EXEC BAD ACCESS int the main function with no reasons…
Turns out, pushing multiple view controllers simultaneously will cause this. Hard to debug that!
In certain locations in my application, if I place a breakpoint and go to that location the code window jumps me to _string.h (which is locked) to this function.
static __inline void *
__inline_memcpy_chk (void *__dest, const void *__src, size_t __len)
When I hit Step I am stuck, and all I see is _string.h. My code still executes and I see my NSLog().
A quick fix is to run in release mode, but in my project I have special code that happens in release. So this isn't really an option.
Does anyone know what is going on?
Thanks.
The problem appears to be caused by my project being a universal build. We created an iPhone version of the build and I can walk through the section of my code where I couldn't before. But then I have the issue of not being able to view my variables.
Oddly enough when I go back to the universal build I don't have the problem in my code, and I can debug normally. Not the greatest fix but at least I can work.
I'm programming an application in Objective-C and I'm getting this error:
MyApp(2121,0xb0185000) malloc: *** error for object 0x1068310: double free
*** set a breakpoint in malloc_error_break to debug
It is happening when I release an NSAutoreleasePool and I can't figure out what object I'm releasing twice.
How do I set his breakpoint?
Is there a way to know what is this "object 0x1068310"?
When an object is "double-freed", the most common cause is that you're (unnecessarily) releasing an autoreleased object, and it is later autoreleased when the containing autorelease pool is emptied.
I've found that the best way to track down the extra release is to use the NSZombieEnabled environment variable for the affected executable in Xcode. For a quick rundown of how to use it, check out this CocoaDev wiki page. (In addition to this page, Apple has documented some incredibly obscure yet useful tips for debugging code in Xcode, some of which have saved my bacon more than a few times. I suggest checking out this Technical Note on developer.apple.com — link jumps to the section on Cocoa's Foundation framework).
Edit: You can often track the offending object down within the Xcode debugger, but it's often much easier if you use Instruments to assist you. From Xcode, choose Run → Start With Performance Tool → Object Allocations and you should be able to trace the offending object back to where it was created. (This will work best if you're enabled zombies as discussed above.) Note: Snow Leopard adds a Zombies tool to Instruments, accessible from the Run menu as well. Might be worth the $29 alone! ;-)
There is also a related SO question here.
You'll find out what the object is when you break in the debugger. Just look up the call stack and you will find where you free it. That will tell you which object it is.
The easiest way to set the breakpoint is to:
Go to Run -> Show -> Breakpoints (ALT-Command-B)
Scroll to the bottom of the list and add the symbol malloc_error_break
I just want to add my experience in addition to the answer of Quinn Taylor.
In one of my apps, I have to parse and save data into core data objects and later on get these objects to display on the views. In fact, the app works just fine and does not crash at all, until I tried to do a stress test of navigating back and forth multiple times, tried to open multiple views as fast as possible. The app crashes with the above message.
I have tried all the methods that Quinn suggested in his answer and still failed to find out where was the exact cause.
I set NSZombieEnabled=YES, and NSStackLogging=YES, ran the command shell malloc_history to find out why, but still no luck. It always points out to where I save the data into core data objects, in fact, I have checked thousand times the over released objects there, nothing odd.
Running in Instruments with various tools(Allocations, Leaks, etc...) still did not help. Enable the Guard Malloc still got nothing.
Final rescue: I tried to come back to the views where the objects were taken from Core Data and sent a retain message to all of these objects, and took note to these changes. It solved the issue!!!
So, I found out that I failed to retain one, that's exactly the cause. Just want to share my experience so you have another rescue for your app.
Open up the debugger console by pressing Cmd+Shift+R. There, type
break malloc_error_break
to set a breakpoint at the beginning of the malloc_error_break function.
If you want to find out what object is located at address 0x1068310, you can type the following into the debugger console:
print-object 0x1068310
Of course, you have to do this while the object is still alive -- if the object has already been freed by the time you do this, then this will not work.
Please find the below steps for how to find the object which is free and crash the application.
1) Click on the "Breakpoint navigator". 2) Then click on the
"+" button which is below. 3) Add the "Symbolic
Breakpoint..." from the list. 4) Add the
"malloc_error_break" keyword on the "Symbol" option.
Or you can also refer the below GIF presentation.
For me the issue was solved by
(gdb) call (void)_CFAutoreleasePoolPrintPools()
right after the crash. The address at the top of the stack was the address of the culprit. Threw in a retain and voila.
The address given in the log message did not get me anywhere. It never showed up in any of the various Instrumets. Apparently a pointer to some internal data which had already been freed.
Adding a symbolic breakpoint in Xcode 4
Just an update to make this relevant to Xcode 4...
From the Xcode 4 User Guide:
To add a symbolic breakpoint . . .
In the bottom-left corner of the breakpoint navigator, click the Add
button.
Choose Add Symbolic Breakpoint.
Enter the symbol name in the
Symbol field.
Click Done.
This is what the malloc_error_break breakpoint looks like in the Breakpoints window in Xcode.
Need to check the boxes to make it work.
alt text http://www.martijnthe.nl/wp-content/uploads/2009/08/Afbeelding-1.png
Check your classes and look under the dealloc method. Make sure you care calling [super dealloc].
I had this exact same problem and found out I was calling [self dealloc] instead. Just not paying attention.
In Xcode, click left of the line number to set a breakpoint. Then you can launch it by doing a "Build and Debug".
It is recommended to not have object that you create be autorelease since memory is a commodity on the iPhone. Apple recommends explicitly calling release.
To find these kinds of memory and pointer problems in general, you want to run your code against a runtime memory error checker like Valgrind. This should be able to point out lots of things your code is doing wrong, beyond those that cause it to crash.
Valgrind can work on OSX (though it says it's "unsupported and incomplete and buggy"), and with a little hacking someone got it to work on iPhone SDK executables.
Even better you can try Instruments, which is part of XCode. There's a tutorial for running it here.
If malloc_error_break is not helping...
The best way to solve this error is to run instruments with the NSZombies turned on. Instruments will flag you when the Zombie is messaged and you can trace directly back to the line of code.
Snow Leopard required, what a lifesaver though!
This is usually caused by some inspector, such as safari or safari preview. Refer to post or post and question.
Remove the select of AutoMatically Show Web ...., will remove this issue.
Note, just close safari or safari preview will not remove this issue. And you have to deselect both of safari and safari preview.
If this will not do, refer to this answer or post to debug it.