I have this error in objective c
-fobjc-link-runtime it say's file not found. I've been googling but failed to get what caused the error. I'm building it on a xcode4.5 environment. using ios6 as base sdk. Any ideas?
Just had the same issue. Turns out it was due to my having left a -force_load option in the Other Linker Flags, that turned out to be followed by -fobj-link-runtime, causing the linker to think that was a library.
That looks an awful lot like a spurious linker flag that leaked through from some kind of ObjC testing harness.
I.e. you need to go to the build settings editor in Xcode, find whatever is setting that particular flag, and remove it.
Related
What does it mean to have undefined symbols?
There are no errors in the code files themselves and I am NOT using any external libraries.
I DID add a typedef NS_ENUM prior to this linker error occurring.
Where do I add this -v to see invocation?
Here is the error message:
Undefined symbols for architecture x86_64:
"_OBJC_IVAR_$_UIViewController._parentViewController", referenced from:
-[PEPI_LessonController setParentViewController:] in PEPI_LessonController.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
"Undefined Symbols"
Building source code files to an executable file consist of at least two steps:
Compile the source code files to intermediate binary files (often called xyz.o).
Link the intermediate binary files to the final executable file.
The error message "undefined symbols" is a linker message. It may appear even though the compilation process was successful without notice. The linker organizes final memory address relations and it replaces symbols that the compiler had to assume they would be valid later, if all parts of the code would be available. Without this, no modularization would be possible at all.
-v to see invocation
If you build your application in Xcode, then Xcode calls all the compile and link commands for you (CompileC, Ln, Clang ...). But remember that a typical IDE runs only the commands you could run by yourself in the shell. Theoretically, you could develop big applications only in a text editor and a shell. So I suggest take some time and try to copy paste some commands listed in the Xcode build report to a shell :-) You'll learn a lot about the backgrounds. Therefore, in my opinion, -v to see invocation is used while invoking the command in the shell - or in the build settings, if you wish permanently more information.
"External libraries"
Finally, try to clarify "external libraries". To look at the most simple example: even if you write a simple C program and you want to know something trivial like the length of a string, you'll include <glibc.h>. Now this is an external library. It's external to your program code. Are you sure you haven't included external libraries?
Solving linker problems
Linker errors are often confusing and somehow difficult, because details of the linked modules tend to be out of sight. You may find many hints if you enter the error message in a search engine. For example, have a look at here:
Undefined symbols for architecture armv7: "_SCNetworkReachabilityCreateWithAddress"
Even if all components are found for linking, all paths are known etc, they may have the wrong version or else.
It means it can't find the property parentViewController and method setParentViewController when linking your object files files. The most common cause for these types of errors is not linking a library or framework in your projects target. UIViewController is part of UIKit so I'd be surprised if it's not already linked. Is this an OSX project and your trying to use UIViewcontroller instead of NSViewController?
In my case I had forgotten to add the .m file to all the same targets as the .h and that's what caused this issue. In case it helps anyone thought I'd mention here... double check your target memberships!
I try to build a static library which "Implicitly link Objective-C Runtime Support", but build fail at link step with the next message:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/libtool: unknown option character 'f' in: -fobjc-link-runtime
I have no idea why this happens, so if you know please help me.
The libtool command doesn't take a -fobjc-link-runtime argument to it. It sounds like this erroneously snuck into your Xcode project. I would suggest the following:
Open Xcode
Select your project and the Build Settings tab
In the Search box type in -fobjc-link-runtime and there should be at least one line in the Build Settings that corresponds
It the item isn't on a compiler-related line, try removing it and re-building
If you don't find it, then it sounds like the libtool arguments are somehow unexpectedly including the arguments from the compiler.
If this is the case, which version of Xcode, and which compiler are you using?
I'm building an ARC iphone app, and about to integrate the addThis ios library.
I get the following error:
ld: duplicate symbol _OBJC_CLASS_$_Facebook in /Users/mars/Desktop/Pst/trunk/Pst/ThirdPartyLibs/FBConnect/FacebookSDK/FacebookSDK.framework/FacebookSDK(Facebook.o) and /Users/mars/Library/Developer/Xcode/DerivedData/Pst-bqmphjiqldalzsankfvxugsurcdj/Build/Intermediates/Pst.build/Debug-iphonesimulator/Pst.build/Objects-normal/i386/Facebook.o for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)
I've double checked with my Compile Resource, and only 1 facebook.m is present.
I've also put "-fno-objc-arc" in my compiler flags for those library files because they are built without ARC
Any help would be really appreciated!!
I've got the same error when followed the instruction to drag ThirdPartyLibs to my project. It had added both FBConnect and FacebookSDK to my project.
If you open the AddThisDemo project, which comes with the library, you will see that only FacebookSDK and DeprecatedHeaders were added (not entire FBConnect). I have recreated this structure in my project and that had solved my issue.
Hope that helps!
For anyone with this issue but these answers are not helping: if you created one custom class and called it Facebook.h/.m, just change its name and after it, no more linkage errors.
You have a #import "facebook.m" in one of your files where you should have put #import "facebook.h".
Some libraries require the -all_load linker flag when linking to an Xcode project. However, this leads to a linker error if there are symbol conflicts among libraries. The solution is to use -force_load, which effectively lets you use -all_load on some libraries, but not on others.
However, this in turn leads to a new problem, at least for me. Whenever I use -force_load with a relative path to a library, the linker always finds symbol conflicts between the library and itself. It appears that the linker thinks that the library with its absolute path and the library with its relative path are different libraries, and therefore finds conflicts between the library and itself.
I can avoid this by using an absolute path with the flag. But this is not a wonderful solution, as it is convenient to keep source code for libraries within my documents directory. But the path to the documents directory will be different on other machines.
Question: Can anyone get force_load to work with a relative path to the library?
EDIT: for background information, see this question
With Xcode 4, if you include the library project into your app project, then you can add this to the Other Linker Flags:
-force_load $(BUILT_PRODUCTS_DIR)/<library_name.a>
You still need the dependency, and you need to add the library in the Link Phase list of frameworks and libraries too.
EDIT: Apple now says as of some Xcode 4 release that you can simply use this linker flag: "-ObjC" to get libraries with categories to properly load. That flag is working just fine for me in Xcode 5. People are still up voting this answer, but I suspect that the -ObjC flag is the best solution now.
This worked for me. Like the above answers you still need to include the library in the project.
-force_load $(SRCROOT)/pathToLibraryFromProject/libname.a
For the path it's just the folders in your project that lead to where you put your library, for example BaseFoler/Subfolder/libName.a.
Is there an Objective-C syntax checker?
I have tried gcc -fsyntax-only but it is not really 'syntax only'. It still produces errors if run on an individual implementation file which has references to external frameworks.
I am looking for something that can perform a syntax check on individual header or implementation files without attempting to link or produce object files.
Can gcc do this with additional flags I am unaware of, or is there another tool up to this task?
I want to do this from the command-line. Can xcodebuild do this for an individual file? Running xcodebuild for the entire project to check the syntax of one file is a bit much.
There's no way for it to check the syntax without it knowing about the header files for the frameworks you are using. You need to use the -framework flag to include the relevant header files.
You could try using clang -fsyntax-only instead, especially if you're using 10.6/Xcode 3.2. Clang/LLVM has much better separation between the parser and the other parts of the compiler chain. You can find clang in /Developer/usr/bin.
So after trawling through the gcc man page I discovered the -F flag which lets you add a framework directory to the list of directories gcc searches for header files.
This solves my issue.
Use it like this: gcc -fsyntax-only -ObjC -F/Path/To/A/Framework -F/Path/To/Another/Framework File.m
You can compile a single file in Xcode[1] using Build->Compile (cmd-K) which is effectively a syntax check (there's no linking step).
[1] I assume you're using Xcode, as there's little point in using Objective-C without OS X (really the Cocoa frameworks).