问题
I have started trying to use SDL in Xcode 4.3.2 so I started up a Cocoa application for Mac OS X and connected all my frameworks : OpenGL, SDL etc. I don't have SDL_Image, SDL_Mixer etc. (Do I need these?) When I try to compile the project that just has SDLmain.h and SDLmain.m I get this error:
Undefined symbols for architecture x86_64: "_SDL_main", referenced from: -[SDLMain applicationDidFinishLaunching:] in SDLMain.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation)
回答1:
I was having the same issue with SDL 1.2.15 on Xcode 4.5 and OS X 10.7, turned out the problem was that I added SDLMain.m and SDLMain.h (according to a suggestion on the libSDL website about OS X frameworks) to an existing SDL project which messed up with main. Bottom line is that you don't need those files just because you are using Cocoa -- SDL's own test apps don't use it either and run just fine on OS X.
来源：https://stackoverflow.com/questions/11032157/sdl-in-xcode-4-3-2-sdlmain-o-undefined-symbols