I spent 1 hour on solving a bug: i was releasing an object that I didn't have ownership (ie I didn't send it copy, alloc, new).
The analyzer (Cmd-Shif-A) didn't detect that error while it can detect an object that hasn't been released.
I think it's not normal, is it a bug or a "missing functionality"?
Static analysis is not magic; there are many limitations and the analyser that Xcode uses is a work in progress. It is there only as an aid, it can't totally debug your application for you.
If you think you have come across a case where you think the analyser could have found the problem, then report a bug.
Related
I've not worked on this project in quite some time.. When I left it some time in the iOS 8s it ran just fine, however.. on the latest XCode I'm getting many inconsistent EXC_BAD_ACCESS crashes. Now afaik it's requiring a deallocated object. However, the error is lacking where to look. This is quite a big project and like I say, the errors are inconsistent.
I've tried enabling zombie objects, as well as passing it as a starting parameter. However, this is leading me to no joy. I'm expecting something in the debug console with zombies enabled, is this right?
If anyone has any tips on how to find an easier way to debug this, as opposed to tinkering with everything and hoping it works..
EXC_BAD_ACCESS just means that your app is trying to access an invalid memory address. While it is oft caused be a deallocated object, that isn't always the case.
When the app crashes, there should be a crash log or backtrace. Post it as that'll provide clues.
Lovely; a crash entirely in framework code. Seeing as how it is SceneKit that is crashing, I would suggest replacing any graphic assets with new ones and see if that fixes it (even if it doesn't look right). Then check to make sure all of your geometries and layouts are correct.
Have you tried adding a global Exception or Symbolic breakpoint? Those usually help me 99% of the time when I encounter issues without any sort of backtrace.
I've got an app that gets information from a SOAP web service and I want to display the results in a UITableView.
I had a previous version of this app and I'm creating a new version to basically clean things up and get rid of a bunch of legacy code that's deprecated and no longer used.
In the previous version, this worked well. In the new version, not so much.
Basically, the current scenario is returning 3 strings that I'm trying to use as the basis for the data in my UITableView.
I'm struggling with this issue because it's so stinkin' hard to track down EXC_BAD_ACCESS errors!
(Parenthetically, if someone has a way to make the debug experience more like Visual Studio, I'd love to hear it! It's so frustrating to not have any idea which line caused the error, and also to not be able to look through my local variables at the time of the crash to see what's what. I've already added in the exception breakpoint, but that doesn't seem to do much.)
Anyway, the line that's causing the error APPEARS to be:
return [[self Libraries] count];
It occurs in tableView:numberOfRowsInSection:.
The error message I get APPEARS to reference a string that should be stored in the NSMutableArray [self Libraries].
What's going on here?
I'm using ARC, so shouldn't all of my memory management be correctly handled?
I don't have any manual release statements in my code ANYWHERE!
Please help me fix this!
Set NSZombieEnabled, MallocStackLogging, and guard malloc in the debugger. Then, when your App crashes, type this in the gdb console:
(gdb) info malloc-history 0x543216
Replace 0x543216 with the address of the object that caused the crash, and you will get a much more useful stack trace and it should help you pinpoint the exact line in your code that is causing the problem.
See this article for more detailed instructions.
ARC relies on the Apple standard/recommended naming practices. Check that you are not violating any of them.
Just for starters, if "Libraries" is an instance there are are naming issues.
OK, so I feel a little bit silly, but I've got two production machines. On one of them, I had installed a copy of Xcode 4.2 beta alongside the final, production copy. I forgot to uninstall the beta copy and was using it to run my code. As soon as I cleared that up and ran my code against the final, released Xcode 4.2, all works fine again.
As I mentioned to Jonathan Grynspan above, I DO understand Obj-C memory management. For some reason, I was getting a retain/release/release (performed by ARC), and that bug is remedied in the final version.
Thanks for the help in tracking this down! At least I got a definitive answer to WHY the problem existed!
I'm working on an iPhone with a group of people over github. I was added to the project late and just started today. I am unable to build the project which I find extremely annoying. The reason is that Arc forbids synthesizing a property of an objective-c object with unspecified ownership or storage attribute. There 8 errors like this preventing building and over 300 warnings that turn into errors as I fix the errors, i.e. if I were to fix 3 of the 8 errors 3 of the 300 warnings would replace them as errors. So while I could go through and add weak or strong to all these many properties throughout the project it'd be a tad tedious and I'm not entirely sure that it'd be good for the project. The other people I'm working with are surprised I'm having errors and are able to build it. My question is how the heck can they build it? is there a setting somewhere that changes the default from assign to strong or something? thanks in advance this is driving me crazy.
For posterity, this issue is resolved in Xcode 4.4.
I've recently converted my iOS project to ARC. I have two targets in my project. One is the application itself, and the other is a set of GHUnit tests. I have approximately 200 tests that do quite a lot of work in terms of creating and modifying Core Data objects. The Core Data store used by the tests is an in memory store, and is thrown away once the tests are finished (i.e. it is not persisted anywhere).
When my tests have been running a while (they never reach the exact same point before the error is thrown, but it is always around the same tests) the application crashes with an EXC_BAD_ACCESS (Code=2, address=...)
The output in the console is as follows:
I've followed the instructions here in this answer, and set my main.m file of the GHUnit target to use the -fno-objc-arc compiler flag, but that doesn't seem to have helped.
I don't really understand what these errors mean, and searching for them doesn't seem to have helped. My only guess is that I am running out of memory, but I'm not sure why or how, considering ARC should be releasing objects for me.
I'd really appreciate any help anyone can give me to fix this! If you have any questions just leave me a comment and I will get back to you asap!
Thanks!
Chris,
First, As you have a memory exhaustion problem, you should look at your tests running under the Instruments allocation tool. Remember to turn on VM automatic snapshots. Then you should mark the heap multiple times as the tests execute.
Second, while this may be related to ARC, it quite possibly isn't. In general, ARC apps, because they can automatically release objects sooner, have a smaller footprint than MRR apps. The move to a new compiler with different options may just be uncovering a pre-existing problem.
Third, because you are using an in-memory database, my first test would be to just change it to a SQLite DB. It can have a much smaller footprint. (While you may choose to return to in-memory DBs later, we're trying to find the cause of your memory exhaustion. An in-memory DB can use a lot of RAM. Hence, lets take is out of the equation.
Once you've done the 1st and 3rd tasks above, please report back your results.
Andrew
I'm having a severe memory leak issue with my program. I'm using Apple's Instruments to track my leaks, and in the first few seconds after my app starts there are hundreds and hundreds of leaks listed. The problem is none of them seem to tell me where the leak is coming from.
I've gone through all my classes and made sure that anything that was alloced was released at the end, and garbage collection is enabled as well. Another big problem is I tried starting up my app without garbage collection enabled and it just crashes.
Any advice?
Thanks
EDIT: If the source code is needed then I can email it
Your question is tagged with "garbage collection".
Do you have GC turned on? If so, is it a command line tool? Did you call objc_startCollectorThread() as the first item in your main()?
If you have GC turned on, leaks analysis on Leopard will show quite a few false positives in certain circumstances. If you have access to Snow Leopard, I suggest you do the analysis there as the tools are significantly improved.
The clang static analyzer & Instruments are entirely orthogonal. You need to use both because the static analyzer isn't going to find all of the potential leaks in your code. In particular, it won't find situations where -- say -- you have unbounded cache growth or a global mutable set that is rooting your object graphs inadvertently.
Once you have fixed all of the problems the static analyzer finds, then use Instruments.
Try running your project through AnalysisTool and see what it finds. It's essentially a GUI front-end for the Clang Static Analyzer. It will run through your code and find errors such as leaks and bad releases, among many other things. It will then present them to you in a step-by-step manner to help you better understand where you made mistakes.
It's a fantastic tool.