I was given a project file and after opening it up I have noticed NSLog does not print to the console.
I've tried shift + command + c and that didn't work.
The strange thing is if I open any other project they print to console just fine still. However this one does not. Is this an xcode setting? if so why is it only this one project that is effected? and how do I go about fixing it?
1) newer attempt to help
Make sure you're printing out everything from NSLog. There's a toggle you can set in the console window:
2) original attempt to help
Try doing a "#undef NSLog" at the top part of your code and see if "NSLog" works again.
If so, then Dave is correct... you need to search around your code to see where "NSLog" has been redefined.
I know this is an old thread, but I just experienced a case where NSLog suddenly stopped displaying. I don't know what actually caused it but, in my case, a simple restart of Xcode made the problem go away. Just posting in case it helps somebody else.
My application is crashing after play with it 10 min.
And in console nothing is show about this crash and no waring, no logs.
And I am not getting any memory warning.
Please help me.
See Next to stop button your project name will be there click there and go to edit Scheme -> Argument -> Environment Variables -> click on + button and write NSZombieEnabled and then value YES.
It will tell that where exactly your app is crashing.
Try setting your Run Static Analyzer to YES then shift+Command+B. See if you have potential Memory Leaks. Or try running you code with Intruments.
or try this:
Edit Scheme
then add the NSZombieEnabled like the image below.
Try Adding breakpoints in the code to check the point where application is crashing..
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!
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.
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.