I'm beginning IPhone development with XCode 4 and Objectiv-C. Since I think strong debug and IDE knowledge is required to master a language, I'm looking for good resources about the debugging process and XCode.
A problem I faced recently was that, an unknownException was being thrown in a sample code and I couldn't know how to debug it, since it crashed right after jumping into my Main. I think with a better configuration, it would have been much easier to debug !
I've already found this resource : https://developer.apple.com/library/ios/navigation/
But I couldn't find something related to debug in there... Did I miss something ?
Andy, this first is about super basic debugging: http://mobile.tutsplus.com/tutorials/iphone/xcode-debugging_iphone-sdk/
And here you can find two excellent tutorials:
http://www.raywenderlich.com/10209/my-app-crashed-now-what-part-1
http://www.raywenderlich.com/10505/my-app-crashed-now-what-part-2
Easy to make mistakes in Objective-C...
Not having a view attached to your view controller
Sending a message to a deallocated instance. Turn on NSZombieEnabled.
Forgot to add the Framework (e.g. MapKit)
If the crash isn't fixed at this point. Set a breakpoint in your app delegate and just step through every line until it crashes. Move the breakpoint up, run again, and inspect the values.
Apple has a list of what they consider to be the best debugging tricks for iOS here.
There is also a couple of videos on the developer's site. I can never find out how to make a direct link, but there aren't that many videos, so just search for "debug":
https://developer.apple.com/videos/wwdc/2012/
There is also one from last year:
https://developer.apple.com/videos/wwdc/2011/
Access to the developer site requires registration.
Should you ever consider venturing into OS X territory, then here is the Apple-approved debugging magic.
Related
This problem has been KILLING me. I've been working on this app for 8 Months, and I am so close to finishing, I just can't seem to build for device. Building for the simulator works fine, but device always gives me the SAME 2 errors.
The 1st Error:
"Instruction requires a CPU feature not currently enabled"
From googling, I've found this probably means I'm not linking a binary I should be, but I'm not sure.
The 2nd Error:
If you can't read it, it says: Generating JWFNS.app.dSYM ... error: unable to open executable '/Users/ajr1188/Library/Developer/Xcode/DerivedData/JWFNS-azshgysfabycfagnebotitpcyaww/Build/Products/Debug-iphoneos/JWFNS.app/JWFNS'
This is the big one. I cannot seem to build the .app.dSYM file properly. I went in and deleted the build folder, I looked at EVERY stackoverflow question I could find and tried changing any random thing mentioned in another question, but all of it is to no avail. I'm so suck right now. AHH. PLEASE. Any help would be so appreciated!
Maybe your project has become hopelessly corrupted. One thing to try is to start a brand new project and copy/import all your sources/assets into the new project to see if that fixes the problem.
Another less nuclear (but perhaps more time consuming) approach is to binary search the build. Exclude absolutely everything except main.m and see if that fixes the problem. If it does, include half your sources, and buid again....repeat, trying to narrow in on the problem spot. Maybe a file or group of files has received special build settings that don't belong there.
I've had very similar problems, I cant remember the exact error message but it was very similar. Are you able to make a new project that will run on your device?
if so (and I know this sounds bad but it's worth a try) Create a new project and simply copy all the code and resources across and see if it still works. If it doesn't then there is something wrong with you code and you can continue trying to isolate the problem from there.
Hope this is helpful.
check the frameworks you link to. there's a chance that you linked a framework (say quartz) of osx, instead of ios.
Answering in detail is probably going to take looking at your target settings. But it looks like you may be building for the wrong architecture. (It doesn't link, so there is no .dSYM symbol file.) For example, if you have only recently built for device, you probably created your project under an older Xcode, and it may not have the arm6/arm7 settings right.
To check, show the Build Settings for your target (not the project), and filter on Architecture.
Make sure that in build settings the architectures are armv6 and armv7. Also make sure that in .plist file, the "Application requires iPhone environment" is TRUE. Delete "Required device capabilities" in the .plist if present.
Ok
SO recently I've being having a lot of trouble with an application working in debug mode but not working in distribution mode.
Is it possible to use xcode debugging tools such as break points and variable tracing with an adhoc distribution build of an app?
If it's not how would one usually go about debugging such a thing?
Assuming that your crash logs aren't giving you any clues (you'll need to hook up to the device to get them) there are lots of things you can do.
But I'd start by looking at the crash logs ... the clues will be there and don't forget Apple make distribution crash logs available to you through iTunesConnect.
1) Copious logging is one thing. Lots of developers use a switch so that in debug, logs go to the console but for other builds they are dropped. Consider a different option where you log to a file instead. You could then push the log files to a remote server for debugging. It's a bit of a slog to set this all up, but once you've done it, you'll wonder how you ever lived without it.
2) Another option is to use Flurry and log events when you detect that things have gone wrong. This can cover more controlled problems when things aren't as expected rather than random crashes. This can be a useful feature for released apps provided your terms and conditions are clear about what data you are logging and why.
3) Make sure you do a clean build, I'm sure you've already done this, but sometimes it clears these issues.
4) Are you using external libraries / modules? I've come across issues with older versions of TT where the arm6/7 build settings were wrong and this was causing issues for distribution builds. Basically check through the build settings for each profile and make sure it is what you expect.
5) Suspect a race condition. In distribution mode (often because the logging is turned off) you will find that your application runs a little bit faster. That can reveal timing issue bugs in badly written code.
So yes ... there is a lot you can do ... you just can't attach the debugger ;-)
Not possible to debug an application in distribution mode.
The build configuration difference between Distribution, Debug, and Release is really whatever parameters you have set for that in XCode. If your Distribution config is giving you problems and the release isn't, the easiest way to fix it is to go back through Apple's steps on copying the Release config and making the changes to make it a Distribution config, like you did originally.
The alternative is to go through every line of the configurations for Release and Distribution and find what's different. The other way is a LOT faster. :)
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Closed 10 years ago.
As most of you have probably seen, Xcode 4 has been released officially today. Now I know that plenty of devs out there have been using the preview versions, and it'd be great if people could post any great tips, tricks, or keyboard shortcuts they've learned using those version now they're no longer under NDA. This could be especially useful for those upgrading from Xcode 3 (like me, downloading right now).
Note: Apple have released a 'transition guide' that has plenty of stuff in about getting from version 3 to version 4, but I bet there are loads of great tricks people out there have learned that aren't in there.
I liked reading this Blog: Pilky.me - Xcode 4: the super mega awesome review.
It presents a good comparison, I especially liked his conclusion near the end.
Currently I have only one tip for Xcode 3 users - don't use xcode 4 unless you have free time to start learning again and/or are willing to report lots of bugs. Wait at least until 4.1. There are still lots of bugs unresolved. Nothing is stable. Also Xcode 4 advertises as having single window ui which is nice, but is unstable as U238. Also - it's probably single thing that is good about new Xcode 4. So here are some of my headaches currently:
There is no possibility to commit whole project (except for separately selected modified files);
There is no possibility to push (if SMC is git). At least I haven't found that;
Since symbol indexing is broken you cannot:
see normal syntax highlight;
jump to certain symbol definitions;
Jump bar is just one big misunderstanding:
Previously comfortable Ctrl+2 shortcut from Xcode 3 which lists method names and pragma marks has now become finger breaking Ctrl+6 (emacs user's rejoice</flamewar>).
There is no direct button to switch between interface and implementation files.
If you have 13.3" macbook[pro] - don't even try to use navigators with utilities (inspectors or libraries).
Also transition guide is made for working Xcode 4 which it is far from.
Update 1:
There is no such thing as "Build & Run". Only build, build for running, build for testing, build for profiling, build for archiving. Then just run without building and run without profiling. AFAIK it supposed to be easier so summa summarum - 8 actions instead of 1. Go figure.
So these are only few of my instantly found glitches for Xcode 4.
P.S. probably will be updating this in upcoming few days.
#Ohmu: The 3-finger up/down trackpad/magic mouse swipe gesture for switching between header (.h) and implementation (.m) files still works a treat.
XCode 4 has a lot of awesome new features. I'd recommend starting to adjust to it by watching last year's WWDC2010 videos - they dedicated a lot of time to going through some of the new stuff.
I love the new assistant mode - it makes it really easy to navigate through your interface/implementation files. This mode also allows you to create your user interfaces alongside your controller classes, which makes development both easier and more effective than doing it in two completely separate programs!
The jump bar (found along the top of your source code) is a really fast way to leap about your project, making it really easy to get exactly to the place in your code that you're interested in.
The version control viewer makes it really easy to track changes. I now use SVN for all my projects, even the ones I work on alone because it really makes it clear to see how the project has evolved over time.
There are settings to set how your layout changes and what's displayed when you build, when you run, when you end a run etc. etc. which I'm also finding really useful because you want to see different things when you'e debugging to when you're back in your code. It's really nice that Xcode helps you easily arrange your layout to exactly how you want for different scenarios.
The code templates (which can be found in the toggleable right-hand-side toolbar) are also really useful, and you can create your own in order to quickly get code you often write down.
Some more subtle things that I've grown to like:
The 'Fix It' feature works really well for quickly replacing typos. I find I don't even have to read the correction Fix It will make because the fix is so natural.
Control-I short cut for re-indenting code. This is really useful if you add a new pair of braces round your code and you want to quickly reformat. I don't think there was a nice shortcut for this in Xcode 3.
Hitting the escape key to bring up autocomplete suggestions seems to bring up much more helpful suggestions in C++, and looks a lot more beautiful all round!
On reliability, I've been using a combination of Xcode 4 and Xcode 3 since Xcode 4 first entered beta. Whenever Xcode 4 packed in for me or wouldn't let me continue with what I wanted to do then I'd just switch over to Xcode 3 as the two are completely compatible. What I got was a really nice transition period and now I'm completly using the latest build (first week of March) so I think it's very stable.
For people that don't like change, this update is going to be hard. It'll be particularly challenging as a lot of the keyboard shortcuts have changed to make new for a lot of new features. The most obvious difference that people are going to oppose is the new all-in-one window layout. I'm sure people will get used to it over time and realize that this way of viewing everything to do with your project is much more effective both in real estate and in navigation terms.
Enjoy using Xcode 4, it really is an amazing improvement over the last version, and it continues to add to the awesome time I'm having writing Mac and iOS applications. :D
More shortcuts than you can shake a stick at here:
http://cocoasamurai.blogspot.com/2011/03/xcode-4-keyboard-shortcuts-now.html
However, completeness is obscuring clarity. For example, I can't straightaway see the shortcut for toggling between a header file and its associated method file. so I recommend one shortcut per answer, and the votes will filter out the best ones.
If you need to open plist files when you are not coding you should keep a copy of XCode3/Applications/Utilities/Property List Editor.
Property List Editor opens within the blink of an eye. But XCode4 takes minutes until it finally shows the plist file.
I guess Apple wants me to replace my 2008 MBPro
NB: Apple's official transition guide has moved/been updated (they didn't update the URL, sigh). It's now at:
http://developer.apple.com/library/mac/documentation/IDEs/Conceptual/Xcode4TransitionGuide/Xcode4TransitionGuide.pdf
The only way for me to like XCode4 is thinking it as a different product.
There's NO evolution over XCode3, just lots of drawbacks for the way I use it.
Who changes (almost all) shortcuts between version of the same software?
Why do I have to learn back from zero how to use and configure my projects? Sounds like punishment, not evolution.
How good is XCode4 for multiple monitors usage? It was clearly designed for a single monitor user, but unlike Xcode3, its UI cannot be as easily (and persistently) changed.
Although it can be disabled (and must), auto code check for errors... So we're back on VB6 now?
I'm a BIG Apple fan, though XCode4 falls short on developer satisfaction due to its lack of customization (compared to XCode3).
Not using XCode3 as a comparison, it is indeed a good IDE.
A frustrated developer,
Cheers.
Risky business: Moving to Xcode 4 will introduce you to a whole new level of strange behaviour, bugs, and pain. E.g. having third-party frameworks (like Three20) in your app, means that you won't be able to build a proper archive, without jumping through various levels of hoops. Don't move to Xcode 4 yet, if you can. If you do, there are some tips below.
Keep your archives safe: ...prior to installing Xcode 4 (from 3). You will lose them (most likely) and with them lose your ability to symbolicate your crash logs.
Adding frameworks: It took me a while to figure this out, and it's nowhere in the docs. You cannot simply do this by right-clicking on the project or a group (like in Xcode 3). You need to go to the project view, select your target and go to "Build Phases" tab. Frameworks can be managed under the "Link Binary with Libraries" section.
Setting target dependencies: Similar to the above, in the "Target Dependencies" section of the "Build Phases" tab.
Delete action-BEWARE: "Delete" (instead of "Remove Reference Only") directly erases the file from your drive. It doesn't go into the Trash, so you cannot recover it.
Text Editor: Here a couple of good ones:
Cmd-clicking on a class name will take you to the implementation (or header) file of that class, cmd-clicking on an object will take you to where the object is declared.
Alt-clicking will open a documenation popup for the object you clicked on.
3-finger sideways gesture to left is the Back button, and goes to your previous file. Gesture to right goes to your next file in the stack. (not sure if this was true in XCode3)
http://pragmaticstudio.com/screencast-tags/xcode4
After watching these great little videos, I instantly warmed to XCode4
They have really sorted it out big-time in so many different places, making conceptual changes such as:
one window = NICE
TextWrap
removed annoying 'stop running + rerun' dialog
good color scheme facility
CMD SHIFT O to locate a header file
The auto completion is sorted out beautifully
clear console button
search & replace NICE
new keybindings NICE
On-the-fly error checking - love it!
As you can see, I made notes over the first 2 days of using it; every time I liked something, or every time something went wrong I would jot it down.
So far I have listed 16 problems, but these are all glitches, such as the colouring system going wrong in certain situations etc... ie all minor things that will get patched up pretty soon in updates.
With the occasional crash, I am not going back to 3.x unless I absolutely have to.
The only thing which really gets my goat is that Apple STILL refuse to support incremental updates. it is totally crazy, and I hope everyone makes a lot of noise about it until they sort it out.
I wondered where per-file compiler flags had gotten to.
Spoiler: Select project, select target, select Build Phases tab, expand Compile Sources phase and rejoice.
My iphone app randomly received this message. I know certain it is memory release problem. However what is the best way to find which object leads this problem. Here are what I have tried
Use Instrument Leak and
ObjectAllocation Trace. Dont saw any
help to know which object have this
problem
Put NSZombieEnabled=YES and project executive ... Dont saw any
help either
Put NSLog everywhere but the EXE_BAD_ACCESS just appear anywhere.
in the debuger, just saw the code
happened in the assembly. like
objc-msg send.
review code many times and read memory management a lot time
and research online a lot time. but
no surprise.
Is there a completed solution to figure out this problem easily. I am a previous Visual C++ programmer, I deal with memory management with years and it is easy to debug and figure out in Visual C++.
If you couldn't see any helpful debug info, I would suggest you find all the places that you are doing a release. It is most likely the case that you have released something that did not need to be released. Code would help us in tracing the issue with you.
As Juan noted, the first stop is the Debugger - what does the debug window give for a stack trace when the app crashes? You should be able to see the line it crashed on... you said in a comment to one response that you saw the crash happen around the lines:
CGPDFDocumnetRef docA=CGPDFDocumentCreatWithURL(myurl);
CGPDFDocumnetRef docB=CGPDFDocumentCreatWithURL(myurl);
Are you really using the same URL object for both calls? Which line is it exactly?
It could be something around the way you make use of the CGPDFDocumentRef, you can find example code how Apple uses them in the QuartzDemo project, file "QuartzImageDrawing.m" (you can find the demo project from the developer portal or embedded in the iPhone documentation with XCode).
XCode is actually pretty powerful, but it does things differently from other IDE's.
In addition to Erich answer, I'd want to add go backward. Start with the most recently added release and work from there.
I ran in to this and it turned out I was releasing an auto-released object that was returned from a convenience method built in to the Cocoa-Touch framework. My problem was as Erich described -- I released this auto-released object. When the system attempted to release it, the program gave the error you are describing.
Regards,Frank
The best way to know what happend is using the xCode Debbuger, give it a try.
You will also receive the message when you don't pass enough parameters to a variable argument method. For example having a NSLog statement like this: NSLog(#"Hello %#");
To check what the error might be
Use NSZombieEnabled.
To activate the NSZombieEnabled facility in your application:
Choose Project > Edit Active Executable to open the executable Info window.
Click Arguments.
Click the add (+) button in the “Variables to be set in the environment” section.
Enter NSZombieEnabled in the Name column and YES in the Value column.
Make sure that the checkmark for the NSZombieEnabled entry is selected.
found this on iPhoneSDK
if set to on the NSZombie, it tells me that I'm releasing an object which is already released and gives me the memory address, very helpful... BUT I can't see which object it's... because the app stopped working...
any help?
thank you
You are looking for: malloc_history
http://www.friday.com/bbum/2010/01/10/using-malloc-to-debug-memory-misuse-in-cocoa/
malloc_history and my post on the same is certainly a correct answer and one way to do this.
However, it is quite likely you can do the same with Instruments, which is also going to be a bit less low level and more straightforward. Under Xcode's Run menu is Run With Performance Tool. Under that, you'll find Zombies.
Running with that, you should be able to see the type of the object being messaged and the retain/release event history.
Try Apple's http://developer.apple.com/library/mac/#documentation/DeveloperTools/Conceptual/InstrumentsUserGuide/Introduction/Introduction.html utility, found in /Developer/Applications/.
A commercial alternative is http://www.omnigroup.com/developer/omniobjectmeter/