How to install libX11-dev on mac os x sierra

Question

I am working on facial landmarks and therefore I have installed dlib on my mac. When I try to execute a program in Xcode from learnopencv.com, the compiler says:

error "DLIB_NO_GUI_SUPPORT is defined so you can't use the GUI code. Turn DLIB_NO_GUI_SUPPORT off if you want to use it."
error "Also make sure you have libx11-dev installed on your system"

I already installed XQuartz. I don't know what to do anymore. Can anyone help me out here?

Erich

Answer 1

I suffered from this error for 3 days and finally fixed with:

xcode-select --install

Ambivert

xcode-select: error: command line tools are already installed, use "Software Update" to install updates – Sodamide