I am getting a crash on my app. It's occurring on dismissModalViewControllerAnimated: message, but... if I set a breakpoint on the NSLog, and step over, it goes through with problem, the EXC_BAD_ACCESS code is 2 and address 0x4:
Thread 1: EXC_BAD_ACCESS(code=2, address=0x4)
I've never had something work with breakpoints and EXC_BAD_ACCESS without them, any ideas?
Please note that my appController is fine. (not released anywhere).
if (appController.modalViewController) {
NSLog(#"==== RETAIN COUNT ====> %d", appController.modalViewController.retainCount);
[appController.modalViewController dismissModalViewControllerAnimated:NO];
}
Retain count logs to 1
This also ONLY happens for iOS 4.2 and my app is running on iPad only
retainCount is useless. Don't call it.
If you have a crash, you have a backtrace. Please post it.
I've never had something work with breakpoints and EXC_BAD_ACCESS
without them, any ideas?
Generally indicates a race condition; your code is dependent on thread A finishing or not finishing something before thread B hits some particular state. Need the backtrace.
Related
I have a window and a window controller which opens when the user clicks a button.
Sometimes I get EXC_BAD_ACCESS(code=1, address=0x0).
0x7fff6f2a59e0: movq (%rax), %rdi
Here is the code:
ChooseProceduresWindowController *chooseProceduresWindowController = [[ChooseProceduresWindowController alloc] initWithWindowNibName:#"ChooseProceduresWindow"];
[NSApp runModalForWindow:[chooseProceduresWindowController window]];
The error appears then runModalForWindow: is called.
I don't get this error every time, but I couldn't find a pattern.
Thanks
the best way to debug EXC_BAD_ACCESS errors is to use NSZombies.
Check out this video for an explanation :
http://youtu.be/LQtPr8bkB3g
NSZombie keeps all your objects in memory when you are trying to release an object that has already been released, so you get closer to finding your bug. As #Mark H said, it is a memory management issue.
Also you could put an NSLog in your dealloc method to have a better idea of what is getting deallocated when at runtime.
That error will be thrown when the object doesn't exist in memory. I'd start looking for memory management issues. The first would be to make sure you are releasing the ChooseProceduresWindowController after using it.
Of the many problems I've been having with my current app, this is one of the most annoying.
In the simulator the login dialog works fine, however on a device it's just a frozen white box and the console prints the following:
void SendDelegateMessage(NSInvocation*): delegate
(webView:resource:willSendRequest:redirectResponse:fromDataSource:)
failed to return after waiting 10 seconds. main run loop mode: kCFRunLoopDefaultMode
I've looked this up but I'm still not sure what it means.
If I try switching
[self authorizeWithFBAppAuth:NO safariAuth:NO];
to
[self authorizeWithFBAppAuth:NO safariAuth:YES];
it switches to the safari app to verify but this somehow kills my app with an error which says ReturnNotPermittedKillClient.
Has anyone experienced a similar problem? On my last app it just worked without any of these issues, and as far as I can see I've done everything the same way this time. However this project was inherited from someone else so there may be underlying causes that I am not aware of.
Edit: Just tried moving the login request from didFinishLaunchingWithOptions to a point in the intro screen class where everything else has already been loaded, just in case it was a memory issue caused by too many tasks trying to run at the same time. This time the error message didn't appear, however the login box still remained white and then closed the app a few seconds later.
Edit2: Seems like it's simply a memory error. I changed all variables which I had previously released to be retained, which has fixed the problem on my 3GS. However on my iPad 1 the problem persists. Incidentally, when changing shouldAutorotateToInterfaceOrientation from using landscaperight to using landscaperight or landscapeleft, when I rotate the iPad I get a memory warning and then the same crash. In both cases there are no debug error messages other than the memory warning, and the app just closes down - there is no breakpoint etc to see where the issue lies.
if you are using the webview then we need to do this first b4 moving to next view .delegate = nil;
This might be what you want:
There are other branches of this in NSObject in the documentation.
Code:
[self performSelector: withObject: afterDelay: ]
The problem was simply down to memory. After changing the way it loads images, sounds etc the problem has gone away.
I have a simple UITableView application that I just converted to ARC. The conversion supposedly went fine, and the app launches now, but if I navigate into a DetailView, then try to jump back to the RootView, I get a BAD_EXC_ACCESS error in main.m, and a crash. I tried turning on Zombie objects, and that stops the crash, but I also don't get anything in the console telling me what was happening. I turned off ARC, and again, no crash, but also no more info on what was causing it in the first place.
Any ideas on how to debug this would be greatly appreciated.
BAD_EXC_ACCESS are a little tricky, mainly because they don't show up at the offending line which causes the error. Using lldb, you can use thread backtrace to get an idea of what is causing it. This answer contains a great answer with a few ideas on how to troubleshoot similar problems.
Right now my app should only supports Portrait. On Summary/Supported Device Orientations I have only selected Portrait so I'm hoping that my app will not rotate. I was testing the app on a device and suddenly I'm getting the following error randomly:
[UIButtonContent deviceOrientationDidChange:]: unrecognized selector sent to instance
It happens when I rotate the device SOMETIMES, is not consistent, and is not always over UIBUttonContent. I supposed that if I only select Portrait, deviceOrientationDidChange should not be called or should be ignored.
Other times my app crashes with an EXC_BAD_ACCESS (code=1, address=something) but it happens when I rotate the device so I'm guessing that both errors are related.
I don't know what to do with this, it's hard to debug because I don't have feedback, the All Exceptions Breakpoint is not being called, so I don't know where and exactly why this is happening. Any idea on how to debug this is welcome.
These are the classic signs of a memory management error. You have over-released some object and it has been deallocated while something else still references it. Later, something messages it. In some cases a new object has taken its place, but that object doesn't understand the messages it's receiving. In other cases, there's no valid object and you get a crash.
Edited to second the advice to use the Zombies instrument to find the over-release.
Do you have a class that should be called with deviceOrientationDidChange:? When this happens, it usually means that you have a dangling reference to a deallocated object. You should try profiling your app with Instruments in "Zombies" mode.
I solved this issue a long time ago, but I think is good to share what actually helped me on this case.
After trying everything with no results with Instruments I started debugging old-school. I had an idea of "where" the error was so I just commented all the code on that section. I was right, the bug just disappeared along with some functionalities. After that I made "binary uncommenting" (uncomment one half) till I got the bug line. It was a third party library, I had an object that was not being released properly.
I'm getting an EXC_BAD_ACCESS with my iPhone app on 0x01ad809b <+0015> mov 0x8(%edx),%edi
I have NSZombieEnabled set to YES but I'm not seeing any class printed out in the debugger like I normally do.
Is there another way to debug this problem?
You have a crash caused, most likely, by corruption of memory, using a variable that isn't initialized, and/or casting a non-object type to an object.
First, post the backtrace of the crash. That will provide more context.
Second, try Build and Analyze. Fix any of the problems that it identifies.
Finally, if this is a new crash, go back to a revision right before the crash and then roll forward until you hit the crash. What are the changes made over that span of time?
With more context -- the crash log, in particular (or backtrace, at the least) -- more specific debugging techniques can be offered.
You can select Breakpoint navigator and add breakpoint on all exceptions. Maybe it will help.
Try with malloc info as well.
Use Instruments to Profile and detect zombies instead.
Change the build target to the Simulator
In the Build menu, select Profile
Instruments will open, then select the Zombies instrument
This automatically sets up the NSZombieEnabled flag and will popup a message whenever a dealloced object is messaged. Clicking the disclosure will show the memory management events of the object.