iPhone SDK linking errors with static library

Question

I've built my own static library with components to be reused in my project, and recently had the need to update a bunch of classes. Specifically, some methods' signatures were changed due to the fact that some classes changed names.

What happens now is that the library compiles fine on its own, but, when added to an app project, the project fails to link:

Ld build/Sucursales.build/Debug-iphoneos/Sucursales.build/Objects-normal/armv6/Sucursales normal armv6
cd /Users/nameghino/src/Sucursales
setenv IPHONEOS_DEPLOYMENT_TARGET 3.1
setenv PATH "/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin:/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc-4.2 -arch armv6 -isysroot /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS3.2.sdk -L/Users/nameghino/src/Sucursales/build/Debug-iphoneos -L/Users/nameghino/src/Sucursales/../../Library/MyLibraries/MSSharedLibrary-1.0.0 -F/Users/nameghino/src/Sucursales/build/Debug-iphoneos -filelist /Users/nameghino/src/Sucursales/build/Sucursales.build/Debug-iphoneos/Sucursales.build/Objects-normal/armv6/Sucursales.LinkFileList -dead_strip -lxml2 -ObjC -all_load -miphoneos-version-min=3.1 -framework Foundation -framework UIKit -framework CoreGraphics -lsqlite3.0 -framework CoreLocation -framework MapKit -lxml2 /Users/nameghino/src/MSSharedComponents/Frameworks/MSSharedLibrary/build/Debug-iphoneos/libMSSharedLibrary.a -o /Users/nameghino/src/Sucursales/build/Sucursales.build/Debug-iphoneos/Sucursales.build/Objects-normal/armv6/Sucursales

Undefined symbols:
  "_OBJC_CLASS_$_DataCatalogService_GetSingleRow", referenced from:
      objc-class-ref-to-DataCatalogService_GetSingleRow in libMSSharedLibrary.a(MSDataCatalogSpecification.o)
  **"_OBJC_CLASS_$_DataCatalogService_ArrayOfString", referenced from:
      objc-class-ref-to-DataCatalogService_ArrayOfString in libMSSharedLibrary.a(MSDataCatalogSpecification.o)
  "_OBJC_CLASS_$_DataCatalogService_GetSingleRowResponse", referenced from:
      objc-class-ref-to-DataCatalogService_GetSingleRowResponse in libMSSharedLibrary.a(MSSingleRowResultsParser.o)
  "_OBJC_CLASS_$_DataCatalogService_GetMultiRowResponse", referenced from:
      objc-class-ref-to-DataCatalogService_GetMultiRowResponse in libMSSharedLibrary.a(MSMultiRowResultsParser.o)
  "_OBJC_CLASS_$_DataCatalogService_GetMultiRow", referenced from:
      objc-class-ref-to-DataCatalogService_GetMultiRow in libMSSharedLibrary.a(MSDataCatalogSpecification.o)
  "_OBJC_CLASS_$_DataCatalogService_HelloWorldResponse", referenced from:
      objc-class-ref-to-DataCatalogService_HelloWorldResponse in libMSSharedLibrary.a(DataCatalogService.o)
ld: symbol(s) not found
collect2: ld returned 1 exit status**

The curious thing is that after a lot of project cleanups (both in the app and the lib projects), I still get the same issue. Even after starting a new project, the problem is still there.

I've also taken care to restart Xcode between a clean and a build a couple of times, but no good.

Any ideas on where to look?

Answer 1

Have you added the library as a dependency to the project? See Xcode 3.1.1 and static libraries

If you drill down into your target, does the library name appear in the "Link binary with libraries" group?

Look at the log for the compiler/linker output. Find the call to the linker. Does your library appear on the list of static libraries to link in?

Answer 2

Yes I solved this error .. a Big Thanks to @Shaggy Frog

Error

I was using some YouTube classes and its giving me below error

Solution

We need to add the Lib Classes to "Compiler Sources" in "Build Phases" option.

1. Go to Project's Build Phases and click on Compiler Sources option (see below screen).

   

2. Then Add the classes here

now make Project Clean and Go for Build.

Hope it helps :)

Answer 3

I just encountered the same linker error. I discovered through trial and error that it was because I was invoking isKindOfClass. I'm not sure why this causes the linker to barf, but hopefully this information helps out.

The class in question, OrderItem, is a child of NSManagedObject; in other words, it's an automatically-generated Core Data entity class.

Specifically, here was the linker error:

"_OBJC_CLASS_$_OrderItem", referenced from:
objc-class-ref-to-OrderItem in libmyStaticLib.a(MyTableViewController.o)
ld: symbol(s) not found
collect2: ld returned 1 exit status

And here was the offending code:

- (void)handleButtonTapWithObject:(id)object
{
    // This must be an OrderItem or else we don't want to touch it:
    if ( NO == [object isKindOfClass:[OrderItem class]] ) // <-- OFFENDING CODE
    {
        NSLog(@"Object parameter is of unexpected type.");
        return;
    }

My workaround was simply to omit the test that ensures 'object' is an OrderItem. The code is not as secure without this test, but the linker error went away. I'd be curious to know if I am going about this test wrong, and perhaps there is a better way of doing this.

Answer 4

I just found if you are using xcode 4 you should drag and drop the library project, then go to your target settings, then in the summary tab in linked frameworks and libraries add your library and done.

Hope it will help someone.