I'm sorry that I found the wrong header file location. I shouldn't use the Internet to help you prepare it or use the default one. You still have to prepare the specific header file location yourself!
Replace the fifth line from the bottom with the following
'/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include'

Run echo | clang -std=c++11 -stdlib=libc++ -v -E -x c++ - to find the system header file and add it to -isystem. If you use homebrew to install various packages, you also need to add include to -isystem, which should be '/usr/local/include',.
My ycm_config looks like this

 53 'c++',
 54 '-isystem', #Mark as system header
 55 #Using `echo | clang -std=c++11 -stdlib=libc++ -v -E -x c++ -` to generate the following infos
 56 '/usr/local/include',
 57 '-isystem',
 58 '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1',
 59 '-isystem',
 60 '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/7.0.0/include',
 61 '-isystem',
 62 '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include',
 63 '-isystem',
 64 '/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include',
 65 '-isystem',
 66 '/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/System/Library/Frameworks',