Q:

Include Eigen library for Xcode project via CMake/CMakeLists.txt

I've got the following CMakeLists.txt (in my "project" folder) file for my project. 
# define new project
PROJECT(SETUPMARKERTEST)
CMAKE_MINIMUM_REQUIRED(VERSION 2.8.0 FATAL_ERROR)

if(UNIX)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
endif(UNIX)

# Set static build for GLFW
SET(BUILD_SHED_LIBS OFF)
ADD_SUBDIRECTORY(ext/glfw-3.1.1)

# Set shared lib build for the rest
SET(BUILD_SHARED_LIBS ON)

# Find dependencies
SET(EIGEN_INCLUDE_DIR "${CMAKE_SOURCE_DIR}/ext/Eigen-3.1.2")
FIND_PACKAGE(OpenCV REQUIRED)

# Set header and source files
SET(MAR_Test_SOURCES
    src/main.cpp
    src/MarkerTracker.h src/MarkerTracker.cpp
    src/PoseEstimation.h src/PoseEstimation.cpp
)

# define executable
ADD_EXECUTABLE(${PROJECT_NAME} ${MAR_Test_SOURCES})

# define additional include directories and linking targets
INCLUDE_DIRECTORIES("ext/glfw-3.1.1/include" ${EIGEN_INCLUDE_DIR} ${OpenCV_INCLUDE_DIRS})
TARGET_LINK_LIBRARIES(${PROJECT_NAME} ${OpenCV_LIBS} glfw ${OPENGL_glu_LIBRARY} ${GLFW_LIBRARIES})

And my Eigen folder is in "project/ext/Eigen/3.1.2/Eigen/". 
Somehow when I created my project for Xcode (in "project/buildXcode/" with Cmake .. -G "Xcode") and run it, Xcode throws me the error:

So I guess there is some error in my CMakeLists.txt, unfortunately I received that file and I'm new to CMake and thus didn't write it on my own nor am I very skilled with CMake. 
Do you know what causes the error and can you fix the CMakeLists.txt that my project runs with the Eigen library? 

A:

Unfortunately it looks like windows is having no problem with this, whereas mac is bleating. 
You just have to use
#include <Eigen/Dense>
instead of
#include <Eigen\Dense>
...pretty stupid error.