"Header Search Paths" vs. "User Header Search Paths" in Xcode?

What is header search path in Xcode?

Xcode uses Clang which has GCC compatible command set. GCC has an option -Idir which adds system header searching paths. And this option is accessible via HEADER_SEARCH_PATHS in Xcode project build setting.

What is Srcroot?

$(SRCROOT) (aka $(SOURCE_ROOT) ) is a path to your location where a . xcodeproj is. It is simple to check, just put it in a field and Xcode gives you a tip. Follow this answer to receive notifications.

Use the User Header Search Paths for paths you want searched for #include "..." and use the Header Search Paths for #include <...>. Of course, if you check the option to Always Search User Paths, then #include <...> will also work for the user paths.