Mach-O Linker Error on Xcode 4.6

Question

I have an iOS app on Xcode 4.6 and when I recently tried to build and run in the iPhone 6.1 simulator I got a "Mach-O Linker Error." It continued to say:

ld: 17 duplicate symbols for architecture i386 clang: error: linker command failed with exit code 1 (use -v to see invocation)

Does anyone know how to solve this?

Thanks so much!

Solution 1

Just go to "Build Phases" -> "Compile Sources" and look for duplicate of classes.

Solution 2

Check if you have "*.m" files in your #import ! It appears that was my mistake...

Solution 3

1. Quit Xcode
2. Restart the System
3. Select Xcode -> Preferences -> Locations
4. In Locations, you will see 'Derived Data'. Click on the arrow icon right next to the path.
5. This will open a folder containing 'Derived Data', delete it.

6. Clean the Product and Run

   if still not works then

   Build Settings > Enable Bitcode > No

Solution 4

In my example, I declared

extern NSString const *keyString

in two different files. I renamed one of them and it solved my problem.

Solution 5

In my case it was constants.

NSString *const cellID = @"cellID";

This line was written in two .m files. After appending static keyword at the start the problem was resolved.

This issue can be recreated in a new project too. You would think that defining constants in the different .m files won't have any effect as they are private. But I don't know how the compiler is handling stuffs behind the scene. On top of that when you tap the issue from issue navigator it doesn't open up a page in the editor like it does for any other issue. Really frustrating.

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Comments

[Itai Spector]

Where is this button?

[MBH]

couldn't find it !? are you serious about it ?