从静态库（.a）中删除方法调用而不重新编译

Question

I'm using a static lib thats giving me a warning when uploading my binary for review by apple.

The method in the static lib that causes the warning(non-public selectors) is never called by me, its corresponding .h is deleted from my proj, but warning still persists.

Given that I know the method name causing the problem, is there a way for me to open/edit this .a and comment/delete the offending piece of code and then use the modified .a in my project.

I don't have access to the .a source to recompile it, and its very old and the creator of it has no contact details for me to track down.

Many Thanks, -Cake

Answer 1

Quick and dirty solution: Open the .a file in a hex editor and change all instances of the name. Leave the function name the same length so that offsets in the file don't change, just change a letter or something like that. I did a quick test, adding a dummy function to a subproject we're building as a static library then tweaking the function name in the .a file (there were five instances, for what that's worth) and everything built okay. I don't see any reason it wouldn't pass the App Store check after that.

I'm really surprised the function was still there in the final build, though—I thought Dead Code Stripping was supposed to clean out any unused code. Huh.

Answer 2

http://opensource.apple.com/source/cctools/cctools-809/

I don't presume to get your bounty, because I haven't provided an easy solution. But yes, it in theory is possible. You have your work cut out for you.

Answer 3

No need to hack the binary files. Just turn off the compiler's "unused selectors" warning: -fno-unused-selectors.

Answer 4

There are several solutions, depending on your lib and project.

In your build settings :

1. Enable " dead code stripping " if possible : If the method is never used (even internally), the symbol will be deleted.

2. Use " Unexported symbol file " : Simply add the symbol into a file and it will be removed from the binary. This will work even if the symbol is used internally.

3. Enable " Deployment Postprocessing " and " Strip Linked Product " with " Strip Style " set to " All symbol "

4. (Not sure) Use " Symbols Hidden by Default ". This is related to the code generation and should not affect linking, but just in case everything above failed...