Duplicate Symbol Error in Objective-C build?

Question

I got this error when I press build+debug:

ld: duplicate symbol .objc_class_name_BlogTableItemCell in /Users/fabian/Development/Workspaces/iphone_experiments         


        

Answer 1

In may case, I followed some instructions to build a newer version of Subversion which directed me to create this symbolic link:

ln -s /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/ /Applications/Xcode.app/Contents/Developer/Toolchains/OSX10.10.xctoolchain

Now I'm really a Windows guy so it wasn't immediately obvious to me - but removing the link fixed it for me (after restarting XCode):

rm /Applications/Xcode.app/Contents/Developer/Toolchains/OSX10.10.xctoolchain

Phew.

(The actual error I got was the one described here: build error duplicate symbols arclite.o)

Answer 2

By mistake the source file was included twice in the Project -> Build Phase -> Compile Sources. Removing one of them solved the problem.

Answer 3

Make sure that you didn't import .m File . For me this happen I added #import "SchoolCommuterHome.m" instead of #import "SchoolCommuterHome.h"

Answer 4

The most common reason for this error is importing an xyz.m file instead of the xyz.h file. Check if your imports contain something like #import "----.m"

Answer 5

For me, changing 'No Common Blocks' from Yes to No ( under Targets->Build Settings->Apple LLVM - Code Generation )

Answer 6

Just to add; Using Xcode to generate subclassed managed objects (Core Data) can sometimes duplicate the generated files. For me the fix was to delete the generated files and re-generate them.