Linker error: symbol(s) not found

Question

Level 1

9 points

Linker error: symbol(s) not found

Hello everyone,

I'm building my first Cocoa app (well, other than my "hello world"). I'm running into a strange problem when I try to build. The linker gives me the following error when I try to init a custom class (called 'RailsApp'):

Undefined symbols:
".objc class_nameRailsApp", referenced from:
literal-pointer@ _OBJC@__clsrefs@RailsApp in MainController.o
ld: symbol(s) not found
collect2: ld returned 1 exit status

Now, there is an import statement in the header file to the 'RailsApp' header file. I've tried moving this around, etc to no avail. I really don't know what else I should do.

If anyone can help a beginner it'd be greatly appreciated!

Ernest

Macbook Pro, Mac OS X (10.5.2)

Posted on Mar 16, 2008 7:37 PM

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Answer 1

solid_root Author

Level 1

9 points

Mar 16, 2008 8:04 PM in response to solid_root

Okay, I figured this one out. I added the implementation file to "Compile Sources" on the target in question. I though XCode would be smart enough to figure out I wanted to compile an implementation file, but guess not...

Now I'm having another issue: I can build just fine, but the **** application just won't launch! If I try to launch it manually by right clicking on it and running it, XCode gets a bunch of errors and basically forces me to quit..

This is starting to be a real pain in the ***. I've got to say, the Mac dev tools seem incredibly dates (and buggy)

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Answer 2

solid_root Author

Level 1

9 points

Mar 16, 2008 8:07 PM in response to solid_root

Internal error:

Assertion failed: [NSThread isMainThread]

is the first error I get.

Basically, it seems to fail some assertions and gives me the option to continue or quit. If I hit continue enough times, I can get back to XCode. But I'm starting to not want to... cant anyone help out?

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Answer 3

solid_root Author

Level 1

9 points

Mar 18, 2008 4:53 PM in response to solid_root

Is there anyone that can help? This is really bugging me! (no pun intended)

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Answer 4

Mar 18, 2008 7:00 PM in response to solid_root

Set a breakpoint at the very start of your program. (Click on far right next to the code).
Click on compile and run (in debug mode)
Now it stop in the debugger. Use the console as well to check the status.

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Answer 5

solid_root Author

Level 1

9 points

Mar 18, 2008 7:13 PM in response to Scott Squires1

Hey Scott,

I put a breakpoint on the very first line on main.m:

int main(int argc, char *argv[])

It never even gets hit!

I don't get any warning or errors during compile, yet the very first line never executes. What can be in between those two?!

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Answer 6

Piroshki

Level 1

4 points

Mar 18, 2008 7:16 PM in response to solid_root

Hi solid_root

Having the same error as you - and trying to solve it. I fiddled with all my import statements, but to no avail. Could you let me know how you added the implement to "Compile Sources"? I haven't opened XCode since 2.0, and am feeling VERY rusty...

Thanks for any pointers!

t.

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Answer 7

solid_root Author

Level 1

9 points

Mar 18, 2008 7:21 PM in response to Piroshki

Sure, that part was easy:

1. Expand Targets
2. Expand the target you are compiling to
3. Expand Compile Sources
4. Make sure all your implementation files are listed in there (anything that has the extension 'm'). If a file is missing, just drag it in

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Answer 8

Piroshki

Level 1

4 points

Mar 19, 2008 5:08 AM in response to solid_root

**** - that was indeed easy, and solved the problem. Clearly a bug as for some reason one of my new implementation files ended up in there, but not the other. Fixing that solved my problem - many thanks!

t.

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Answer 9

solid_root Author

Level 1

9 points

Mar 19, 2008 6:12 AM in response to Piroshki

No problem. I agree- it's very counter-intuitive. I would have thought XCode would have added the implementation files automatically to be compiled...

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Answer 10

xsmasher

Level 1

105 points

Jun 12, 2008 7:49 PM in response to solid_root

I had a similar linker problem, and solved it by right-clicking on "Frameworks" and adding the "Existing framework" that contained the missing object.

In my case, I was getting linker errors on_AudioServicesCreateSystemSoundID ,
and had to add the AudioToolbox framework.

Not sure why #import <AudioToolbox/AudioServices.h>
didn't do the trick.

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Answer 11

mpiDev

Level 1

0 points

Sep 19, 2008 12:03 PM in response to solid_root

Thanks for this post, Saved me some trouble.

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Answer 12

DenVogel

Level 1

25 points

Jan 10, 2009 9:35 AM in response to xsmasher

Thanks for sharing this post. Had the same issue. Saved me quite a bit of time. Much appreciated.

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Answer 13

Apr 9, 2009 4:45 PM in response to xsmasher

This was my exact problem as well (AudioToolbox.framework)

Thanks for posting your solution, xsmasher.

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Answer 14

cjcj

Level 1

63 points

May 19, 2009 12:30 PM in response to solid_root

I know this question has been answered - but I thought this might help someone:

I had added the security framework via the method above (right click on frameworks > add existing frameworks...) but only applied it to my Main.app as a target.

I have a small bundled app which implements a 'request for admin password' when running a sudo command within my main app. I had to delete the security framework and add it again to apply it to the both the bundled app as well as my main app.

It's confusing as I hadn't realised it needed to be bound to both - nor in fact realised that the framework, when it exists isn't visible to both - but happy I've solved this problem. Hope this is useful to someone.

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Answer 15

Tech Guru

Level 2

205 points

Jul 12, 2009 8:55 AM in response to cjcj

Hi- Just posting this in case anyone else has a similar problem.

I was getting this same type of error trying to link in the GameKit framework.

I tried deleting the framework (in xcode) and I got the exact same error.. (telling me that it's obviously a link problem and not a code ref problem)

I tried adding back via menu & drag and drop from another app where GameKit is working.... checked targets (only one app, and it's checked).. also made sure GameKit shows up in Link Binary With Libraries folder... no luck, no luck, no luck....

Finally (no idea why I tried this) I went to Finder and found that a copy of the GameKit framework folder was still in my app folder.... as soon as I deleted this, everything linked up just fine

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