How to add DLib to XCode

Build Phases > Link Binary With Libraries

Add libdlib.a

Build Settings > Library Search Paths

Add the directory containing libdlib.a, Like this: ../../../addons/ofxDLib/dlib/lib

Build Settings > Other Linker Flags

Add ../../../addons/ofxDLib/dlib/lib/libdlib.a

Build Settings > OTHER_LDFLAGS

add ../../../addons/ofxDLib/dlib/lib/libdlib.a

Project Navigator

Add /dlib/all.source.cpp to the project (so it compiles with target) source.cpp should now appear in the Build Phases > Compile Sources

Target > Build Settings > Other C++ Flags

Switch off GUI (X11) compilation by adding -DDLIB_NO_GUI_SUPPORT to Other C++ Flags

Target > Build Settings > Header Search Paths

Add the correct directory ( ../../../addons/ofxDLib/dlib/) to

FIX "nil" in /dlib/dlib/graph_cuts/min_cut.h

Just search and Replace every mention of nil and change to no_parent Becaus Clang says it's a reserved keyword.