A little thing about Xcode LLVM C++ Settings

#iOSBySheldon
Apple LLVM 9.0 - Language - C++ Settings

This is an option setting under a Target - Build Settings tab. The idea is to let Xcode (LLVM) to be able to handle C++ functions, if you are using any static framework that  is written in C++.

This is two items that need to be selected(it may be defaulting different values by different Xcode version):
C++ Language Dialect: GNU++14 [-std=gnu++14]
C++ Standard Library: libc++ (LLVM c++ standard library with C++11 support)

14 indicates this version came out in 2014 [1], if you have to use older version, 11 is in the droplist. If you need 98 you can still run some script to achieve it. [2]

See the reference links for more info.

Reference Links:
[1] C++ Standard: http://www.drdobbs.com/cpp/the-c14-standard-what-you-need-to-know/240169034
[2] https://stackoverflow.com/questions/27549390/for-xcode-default-c-language-dialect
[3] https://stackoverflow.com/questions/35592195/many-questions-about-the-various-c-compilers-available-to-me-on-os-x