I'm sure "CMAKE_IOS_DEVELOPER_ROOT" is set correctly，but all header files are not found in logs.

the build commond like this:
cmake -DCMAKE_TOOLCHAIN_FILE=../iOS.cmake -DCMAKE_IOS_DEVELOPER_ROOT=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/ -GXcode ..

the logs like this:

• Toolchain using default iOS SDK: /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS11.2.sdk
  -- The C compiler identification is AppleClang 9.0.0.9000039
  -- Detecting C compiler ABI info
  -- Detecting C compiler ABI info - failed
  -- Detecting C compile features
  -- Detecting C compile features - failed
  -- Could NOT find Git (missing: GIT_EXECUTABLE)
  -- Could NOT find Git (missing: GIT_EXECUTABLE)
  -- Performing Test check_c_compiler_flag__Wno_error_deprecated_declarations
  -- Performing Test check_c_compiler_flag__Wno_error_deprecated_declarations - Failed
  -- Performing Test check_c_compiler_flag__Qunused_arguments
  -- Performing Test check_c_compiler_flag__Qunused_arguments - Failed
  -- Looking for GNU_LIBRARY
  -- Looking for GNU_LIBRARY - not found
  -- Looking for _GNU_SOURCE
  -- Looking for _GNU_SOURCE - not found
  -- Looking for sys/types.h
  -- Looking for sys/types.h - not found
  -- Looking for sys/socket.h
  -- Looking for sys/socket.h - not found
  -- Looking for netinet/in.h
  -- Looking for netinet/in.h - not found
  ... ...

What is the difference between this fork and the code.google.project? Did you alter it in any way and if so, what was added or fixed?

When building with this script for simulator64, the resulting binary is seen in Xcode differently; when linking to it during a simulator build inside Xcode, the following is reported:

building for iOS simulator, but linking in object file built for OSX, for architecture x86_64

find_package(Threads REQUIRED) fails with:

-- Looking for pthread.h - not found
CMake Error at /Applications/CMake.app/Contents/share/cmake-3.6/Modules/FindPackageHandleStandardArgs.cmake:148 (message):
 Could NOT find Threads (missing: Threads_FOUND)
Call Stack (most recent call first):
 /Applications/CMake.app/Contents/share/cmake-3.6/Modules/FindPackageHandleStandardArgs.cmake:388 (_FPHSA_FAILURE_MESSAGE)
 /Applications/CMake.app/Contents/share/cmake-3.6/Modules/FindThreads.cmake:223 (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
 dlib/CMakeLists.txt:195 (find_package)

If I generate normal Xcode macos project and change type to iOS manually, it works and compiles fine.

Is this under the New BSD License like the original? I would like to use it, but wasn't sure about licensing.

The CMAKE_FORCE_CXX_COMPILER macro is deprecated. Instead just set
CMAKE_CXX_COMPILER and allow CMake to identify the compiler.
Call Stack (most recent call first):
toolchain/iOS.cmake:51 (CMAKE_FORCE_CXX_COMPILER)
build.ios/CMakeFiles/3.7.1/CMakeSystem.cmake:6 (include)
CMakeLists.txt

CMake Error at /Users/allen/Desktop/ios-cmake/toolchain/iOS.cmake:149 (message):
No iOS SDK's found in default search path
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk.