转自http://blog.****.net/cyuyanenen/article/details/51444974
警告提示：Invalid C/C++ compiler in target CoreTextMagazine: com.apple.compilers.llvmgcc42
错误提示：Unsupported compiler ‘com.apple.compilers.llvmgcc42’ selected for architecture ‘i386’
Unsupported compiler ‘com.apple.compilers.llvmgcc42’ selected for architecture ‘x86_64’
原因分析：工程使用的编译器版本过低所致，修改编译器版本至最新版本。
解决方案：
Build Settings->Build OPtions->compiler for C/C++/ObjectiveC 
选择： Default compiler (Apple LLVM 7.0)