I have a superweird problem:
I get a crash (EXC_BAD_ACCESS) when running my app with Release as active configuration on my 3.1.3 iPhone 3G. (works well in debug configuration or in simulator , works perfectly on device running iOS4).
My first guess was one setting in the Release configuration was erroneous/missing. In order to test it I just made a duplicate of my debug configuration and surprisingly I get the same error (although configuration is just a copy of the one working).
I don't understand why, with configurations that are supposed to be the same, one is working and not the other one.
If someone want to enlighten me, I am banging my head against the wall.
Thank you
NOTE: base SDK is 4.0 and deployment target is 3.0
Perhaps you have an unassigned local variable. Object-C follows how C does this. So in a release version you cannot assume that any local variable is initialised to 0 whilst in debug you can (in this case I would guess a pointer).
EDIT:
Pass -Wuninitialized to the compiler (or better -Wall) for the compiler to warn on these Apple gcc man page Note only works if optimizer is on.
You should check for memory leaks and handling of memory warnings. The amount of memory is probably the biggest difference between the environments you quote.
In another scenario I once found out that the simulator was faster, and therefore a certain race condition didn't show up, which did show up on the device. That's the second difference in the environments you quote: speed.
Try to pinpoint your crash and investigate from there. NSLog all didReceiveMemoryWarnings. Look for places where you made assumptions, i.e. about static information.
I fixed the problem.
It was three20 library fault. I had updated to the master branch that support iOS 4 but unfortunately this breaks support for 3.1.3. (thing that is not documented apparently)
Anyway I found this post that helped me to spot the problem. I just had to apply this patch and then I was able to run my project on 3.1.3 devices and iOS4 ones
Weird thing: why was it crashing when I was initializing a UIActionSheet (on a line of code not related at all with the Three20 lib)?
Thank you for your help.
Related
I have an app that is crashing on the device (works well in the simulator) which leads me to assume that maybe it's a memory issue...
When it crashes, there is no message whatsoever reported in the console.
It does not crash each time a certain action is taken, it crashes at different points of time always after the app has been running and in use for some time.
I know I'm supposed to ask a more specific question - but if anybody is able to tell me where to start trying to track down a crash that does not report in the console, I would really appreciate it!
I am now using the latest version of XCode (4.2)
Thanks in advance...
It very-well could be a memory issue. If that is where you want to start your diagnostics, you can use the built-in Xcode profiler. In Xcode Product->Profile will get you started.
Maybe setting the NSZombiesEnabled value to YES in Project -> Edit Active Executable -> Arguments -> Variables is also helping; this will show you memory access errors based on accessing released objects. But in that case you should at least get a SIG_ABRT or BAD_ACCESS error ...
You can also log when the app receives a memory warning in the didReceiveMemoryWarning functions of your view controllers - this is called before the system is throwing out stuff when memory gets low. That of course could lead to a crash with nothing showing.
First, relax.
Then read this Technical Note.
Now, follow these steps:
From /Users/<username>/Library/Developer/Xcode/DerivedData remove all folders.
From /Users/<username>/Library/Application Support/iPhone Simulator remove all folders.
Clean your trash.
Remove app from device.
Build and run application on device.
Follow the steps that leads toward a crash.
Now, go to XCode->Window->Organizer and select "Device Logs" your device from the DEVICES pane. Select the most recent of these which has your application's name. Wait for XCode to symbolicate the crashlog. There are two possibilities now:
Its a low memory crash.
Its a memory management related crash.
If its option one, profile your application in Instruments.
If its option two, you should see the stack frame where you application is crashing (or your module's stack). This SO question will be very helpful
If you cannot understand the output (or you think the crashlog is not symbolicating - or that its not your code that's crashing), please post the crash log's crashing thread's stack here and I'll look into it.
PS: in the first section we do the first two steps to make sure there are no left-over .app/.dSYM files which might hinder symbolication later in the process because XCode symbolicator is not that intelligent.
I've imported an iPhone app that I have developed for iOS and am now maintaining it. I've came across a couple of bugs when trying to add to the iPhone's calendar, which I'm happy to try and sort out myself with a bit of debugging.
One problem is that when I go to run the application on the iPhone simulator, it seems to run an older version of the app than the one I am running. I've removed and added another button since then and the old button is still showing when I run it in the simulator. However, when I compile and run this on a device, it loads the correct version and displays the correct version number in the 'about' view.
But... my main problem is that it doesn't seem to debug on the device properly. The app actually works fine except for the calendar problems, but if I put a few breakpoints in so I can see exactly where this is going wrong, it just doesn't seem to step through! The app pauses, and Xcode says the app has paused! I can press step over and continue execution etc and it appears to work, but I can't see it stepping over the code, nor can I hover over variables to see their values.
I've tried reinstalling Xcode multiple times (I did have a problem installing an older version, so I had to wait until the next version was available before Xcode would install).
The stress is: Today is my last day at work, and I'd really like to get this app ready for iOS 5 before I leave.
Has anyone seen these symptoms before? Is there a debug setting that I've missed? Or is it a corrupted installation?
I wish I could help people a bit with more information, but I don't even know where to start looking here. Any code I can post? any settings? (not too familiar with this, I'm a .NET guy usually).
Thanks!
Sorry you're going through a tough moment there Connell; as you said you're not too familiar with all this, I'm laying down a few steps which might help you out. Some are pretty basic, yes, but I've resolved to these steps myself several times when I've encountered similar scenarios;
If you're testing on the simulator, do a 'Reset Content and Settings' from the 'iOS Simulator' main menu. This will remove all old data and settings and give you a clean start.
Do a 'Clean All Targets' from the Build menu. Then go to your physical project folder and delete the Build folder from it altogether before starting to build again.
Restart both XCode and the Simulator (and your Mac too if possible)
Make sure the mode is set to Debug and not Release or Distribution
Even on the device, remove the old app before putting the new one in, and restart it for good measure.
Delete all Provisioning Profiles from the device and install just the one you need.
On the code;
I've noted that the app appears to 'pause' like this a couple of times when I had accidentally created an infinite loop in the code. Double check to see whether there's something which may cause this.
Unless you haven't already done so, throw an NSLog or two in there to see if its really not being executed beyond the breakpoint.
I've had the exact same problem with a project that I started on xcode 3 and then switched to xcode 4. What fixed it for me was changing the compiler in the project settings.
The default compiler up to xcode 3 was gcc, while the default compiler on xcode 4 is LLVM gcc.
Now, I don't know exactly what's the issue that gdb could have with LLVM gcc, but switching the compiler back to gcc in my project settings and doing a clean build fixed my debugging issues.
Might be worth a try.
Have you checked which debugger is being used GDB or LLDB? Select Edit Scheme from the Product menu, and see what the Debugger setting is under the Debug scheme. You could try switching between GDB, LLDB, and None and running in between.
I have an iPhone app that's been in development for about 2 weeks. We recently tried the "release" version of the build on a device, and to our great unhappiness, it crashes in one of the views with an "EXC_BAD_ACCESS".
This crash only occurs on devices, and only in the "release" build. Not only that, but it only happens the first time the app is launched! It is also 100% reproducible.
We have removed the small block of code that deals with data persistence, and have tried re-openning Xcode, cleaning the project, deleting and reinstalling the app, etc., as some other questions suggest.
Do you have any advice for a) what might be causing this problem, and b) how to go about debugging if it only happens in "release"?
Thanks
It turns out there was no problem in the code at all.
The reason it was crashing was that Xcode was trying to attach the debugger to the release build for some reason! We are still trying to figure out why, because we have checked the most obvious places, but I'm sure it won't be too hard to track down.
The build works fine if you install from iTunes or the Xcode organizer instead of building and running from Xcode directly, so it won't affect your end-users at all, as long as you are careful to check for other first-run issues.
We can only guess what the cause might but if it's 100% reproducible, then it should be a good candidate for some fprintf-style debugging.
Figure out the most probable place for the error to occur, and start putting "Got past xxx view initialization" style statements in to start narrowing the problem. It's tedious, but eventually, you'll get there.
In theory fprintf statements could affect the problem. However, it's rare that it does so, so it's a good place to start.
When I start my iPhone application it boots up fine, shows the first settings screen and all after I have given input and pressed save, the debug window says
Debugging Terminated
without any hint to why in the crash logs.
First I thought it was my programming, but then I went ahead and tested the app on multiple 'real' iPhones and it never crashed.
Why does the simulator keeps crashing?
A common cause of crashes on the simulator but not the device and vice versa is using precompiled libraries that were compiled on the other hardware. Check if you've got something compile for ARM that is trying to run on the Intel.
In XCode try Build > Clean All Targets
Have you tried resetting the simulator? iPhone Simulator -> Reset Content and Settings
Then do a clean build of your project.
Annoying :)
Put NSLog statements around where you think that it's crashing and look at the output. That shoud give you more of an idea where the crash is occurring.
If that doesn't help, post the lines causing the crash in the question and see if anyone can help then.
Sam
This tends to happen when you declare a variable and then use it without actually creating it. I would check variables you are using to make sure you are actually creating them before using (i.e. with alloc or the convenience methods).
Something really weird is going on with Xcode and an iPhone project I'm working on, when I'm building for the simulator, the project has 2 active executables (MyApp - iPhone Simulator (2.0) and MyApp - iPhone Simulator (2.1)) Almost all of the time, I want to use the the 2.1 active executable, but Xcode will occasionally silently change to the 2.0 one.
There doesn't seem to be any pattern to this or any trigger that I can notice. Googling has found a couple of people out there who are having the same problem, but no solutions.
Help me stackoverflow-kenobi! You're my only hope!
Ok, it was a bug. The good news: it's fixed in the fresh new 2.2 SDK.
That is weird -- I've been doing iPhone/XCode development for a while, now, and never seen anything like that.
Are you absolutely certain that you're not poking around some place that's causing the change?
Might you have a corrupt XCode or .xcodeproj? If it persists, I'd try re-creating my project and, if that didn't help, reinstalling XCode.
Very strange, indeed...!
I have the same problem. I need to set the active Executable to 2.1 for openAL to work. The pattern I observed is that it switches back everytime I switch to export to the device. Isn't that what happens with you?
I've seen the issue commented a couple of times on the official iphone dev forum, but no solutions. Looks like a bug.
So.. why are you actually doing that? It is probably better, given the nature of the iPhone (with multiple frameworks for multiple architectures), to set up different Targets for your various projects. The executable produced will be the result of the build phases for your targets.