How to build OpenCV 2.4.9 for iOS?

Question

I am following these instructions which belong to the openCV doc, but they are really outdated: iOS4 or iOS5 is mentioned, XCode 4.2 installed in /Developer, etc..

I

Answer 1

Instead of using terminal commands given in the opencv installation guide in official website, use the following commands. Worked for me.

cd OpenCV-2.3.1

mkdir build

cd build

cmake -G "Unix Makefiles" ..

make

sudo make install

Answer 2

As per 3rdParty/libjpeg/CMakeLists.txt:12, jmemansi.c is excluded from build :

if(ANDROID OR IOS)
  ocv_list_filterout(lib_srcs jmemansi.c)
else()
  ocv_list_filterout(lib_srcs jmemnobs.c)
endif()

However, in world module build, the corresponding object file is not excluded from linker input. This can be fixed by filtering out jmemansi.o from linker input :

modules/world/CMakeLists.txt:84

macro(ios_include_3party_libs)
  foreach(l ${ARGN})
    add_dependencies(${the_module} ${l})
    string(REGEX REPLACE "<MODULE_NAME>" "${l}" objpath1 "${CMAKE_BINARY_DIR}/3rdparty/${l}/${objpath0}")
    file(GLOB sources ${CMAKE_SOURCE_DIR}/3rdparty/${l}/*.c)
    foreach(srcname ${sources})
      if(IS_ABSOLUTE "${srcname}")
        file(RELATIVE_PATH srcname "${CMAKE_SOURCE_DIR}/3rdparty/${l}" "${srcname}")
      endif()

      string(REPLACE ".." "__" srcname "${srcname}")
      get_filename_component(srcname_we ${srcname} NAME_WE)
      string(REGEX REPLACE <SRC_NAME_WE> "${srcname_we}" objpath2 "${objpath1}")
      string(REGEX REPLACE <RELATIVE_SRC_NAME> "${srcname}" objpath3 "${objpath2}")

      list(APPEND objlist "\"${objpath3}\"")
    endforeach() # (srcname ${sources})
  endforeach()
  ocv_list_filterout(objlist jmemansi) # <<= dirty fix
endmacro()