XCode5.02真机编译项目，提示：
Undefined symbols for architecture armv7: "_libiconv_open", referenced from: SIX_Utility::U2G(char const*) in SIX_Utility.o SIX_Utility::G2U(char const*) in SIX_Utility.o "_libiconv", referenced from: SIX_Utility::U2G(char const*) in SIX_Utility.o SIX_Utility::G2U(char const*) in SIX_Utility.o "_libiconv_close", referenced from: SIX_Utility::U2G(char const*) in SIX_Utility.o SIX_Utility::G2U(char const*) in SIX_Utility.o ld: symbol(s) not found for architecture armv7 clang: error: linker command failed with exit code 1 (use -v to see invocation)

右键查看iconv_open定义，来到iconv.h，见红色框部分：

 
原来没有定义LIBICONV_PLUG，就会把iconv_open定义为libiconv_open。。。
知道原因就好办了，打开target->build settings，找到preprocessor macros项，把LIBICONV_PLUG增加进宏定义就可以正常编译通过了！