Cocos2d-x Undefined symbols for architecture armv7: "xxtea_decrypt(unsigned char*, 解决方案

Undefined symbols for architecture armv7:
  "xxtea_decrypt(unsigned char*, unsigned int, unsigned char*, unsigned int, unsigned int*)", referenced from:
      cocos2d::FileUtils::getDataFromFile(std::__1::basic_string, std::__1::allocator > const&) in libcocos2d iOS.a(CCFileUtils.o)
ld: symbol(s) not found for architecture armv7
clang: error: linker command failed with exit code 1 (use -v to see invocation)