Refine the cross-compiling toolchain file for iOS.

cmake/cross_compiling/ios.cmake

-# This file is based off of the Platform/Darwin.cmake and Platform/UnixPaths.cmake
-# files which are included with CMake 2.8.4
-# It has been altered for iOS development
-
-# Options:
+# Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
 #
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This is a toolchain file for cross-compiling for iOS, and the
+# configuration largely refers to public toolchain file:
+#    https://raw.githubusercontent.com/leetal/ios-cmake/master/ios.toolchain.cmake
+# and
+#    https://github.com/cristeab/ios-cmake
+#
+# Supports options:
 # IOS_PLATFORM = OS (default) or SIMULATOR
 #   This decides if SDKS will be selected from the iPhoneOS.platform or iPhoneSimulator.platform folders
 #   OS - the default, used to build for iPhone and iPad physical devices, which have an arm arch.
 #   SIMULATOR - used to build for the Simulator platforms, which have an x86 arch.
-#
-# CMAKE_IOS_DEVELOPER_ROOT = automatic(default) or /path/to/platform/Developer folder
+# IOS_ARCH
+#   The archectures wanted to support, such "arm64", "armv7;arm64"
+# IOS_DEPLOYMENT_TARGET
+#   The minimum iOS deployment version, such as "7.0"
+# IOS_ENABLE_BITCODE = ON (default) or OFF
+# IOS_DEVELOPER_ROOT = automatic(default) or /path/to/platform/Developer folder
 #   By default this location is automatcially chosen based on the IOS_PLATFORM value above.
 #   If set manually, it will override the default location and force the user of a particular Developer Platform
-#
-# CMAKE_IOS_SDK_ROOT = automatic(default) or /path/to/platform/Developer/SDKs/SDK folder
-#   By default this location is automatcially chosen based on the CMAKE_IOS_DEVELOPER_ROOT value.
-#   In this case it will always be the most up-to-date SDK found in the CMAKE_IOS_DEVELOPER_ROOT path.
+# IOS_SDK_ROOT = automatic(default) or /path/to/platform/Developer/SDKs/SDK folder
+#   By default this location is automatcially chosen based on the IOS_DEVELOPER_ROOT value.
+#   In this case it will always be the most up-to-date SDK found in the IOS_DEVELOPER_ROOT path.
 #   If set manually, this will force the use of a specific SDK version
 
 # Macros:
-#
 # set_xcode_property (TARGET XCODE_PROPERTY XCODE_VALUE)
 #  A convenience macro for setting xcode specific properties on targets
 #  example: set_xcode_property (myioslib IPHONEOS_DEPLOYMENT_TARGET "3.1")
-#
 # find_host_package (PROGRAM ARGS)
 #  A macro used to find executable programs on the host system, not within the iOS environment.
 #  Thanks to the android-cmake project for providing the command
 
-# Standard settings
-# set (CMAKE_SYSTEM_NAME Darwin)
-set (CMAKE_SYSTEM_VERSION 1)
-set (UNIX True)
-set (APPLE True)
-set (IOS True)
+if(NOT IOS)
+  return()
+endif()
+
+set(CMAKE_SYSTEM_NAME Darwin)
+#set(UNIX ON)
+#set(APPLE ON)
+
+# Get the Xcode version being used.
+execute_process(COMMAND xcodebuild -version
+                OUTPUT_VARIABLE XCODE_VERSION
+                RESULT_VARIABLE XCODE_VERSION_RESULT
+                ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE)
+if(NOT ${XCODE_VERSION_RESULT})
+  string(REGEX MATCH "Xcode [0-9\\.]+" XCODE_VERSION "${XCODE_VERSION}")
+  string(REGEX REPLACE "Xcode ([0-9\\.]+)" "\\1" XCODE_VERSION "${XCODE_VERSION}")
+  message(STATUS "Building with Xcode version: ${XCODE_VERSION}")
+else()
+  message(FATAL_ERROR "Cannot execute xcodebuild, please check whether xcode is installed.")
+endif()
 
 # Required as of cmake 2.8.10
-set (CMAKE_OSX_DEPLOYMENT_TARGET "" CACHE STRING "Force unset of the deployment target for iOS" FORCE)
-
-# Determine the cmake host system version so we know where to find the iOS SDKs
-find_program (CMAKE_UNAME uname /bin /usr/bin /usr/local/bin)
-if (CMAKE_UNAME)
-    exec_program(uname ARGS -r OUTPUT_VARIABLE CMAKE_HOST_SYSTEM_VERSION)
-    string (REGEX REPLACE "^([0-9]+)\\.([0-9]+).*$" "\\1" DARWIN_MAJOR_VERSION "${CMAKE_HOST_SYSTEM_VERSION}")
-endif (CMAKE_UNAME)
-
-# Force the compilers to gcc for iOS
-set (CMAKE_C_COMPILER /usr/bin/gcc)
-set (CMAKE_CXX_COMPILER /usr/bin/g++)
+set(CMAKE_OSX_DEPLOYMENT_TARGET "" CACHE STRING "Force unset of the deployment target for iOS" FORCE)
+
 set(CMAKE_AR ar CACHE FILEPATH "" FORCE)
 set(CMAKE_RANLIB ranlib CACHE FILEPATH "" FORCE)
 set(PKG_CONFIG_EXECUTABLE pkg-config CACHE FILEPATH "" FORCE)
 
 # Setup iOS platform unless specified manually with IOS_PLATFORM
-if (NOT DEFINED IOS_PLATFORM)
-    set (IOS_PLATFORM "OS")
-endif (NOT DEFINED IOS_PLATFORM)
-set (IOS_PLATFORM ${IOS_PLATFORM} CACHE STRING "Type of iOS Platform")
+if(NOT DEFINED IOS_PLATFORM)
+  set(IOS_PLATFORM "OS")
+endif()
+set(IOS_PLATFORM ${IOS_PLATFORM} CACHE STRING "Type of iOS Platform")
+
+# Set the architecture for iOS
+if(NOT DEFINED IOS_ARCH)
+  if(IOS_PLATFORM STREQUAL "OS")
+    set(IOS_ARCH "armv7;armv7s;arm64")
+  elseif(IOS_PLATFORM STREQUAL "SIMULATOR")
+    set(IOS_ARCH "i386;x86_64")
+  elseif(IOS_PLATFORM STREQUAL "WATCHOS")
+    set(IOS_ARCH armv7k)
+  endif()
+endif()
+set(CMAKE_OSX_ARCHITECTURES ${IOS_ARCH} CACHE string  "Build architecture for iOS")
+
+# Specify minimum iOS deployment version
+if(NOT DEFINED IOS_DEPLOYMENT_TARGET)
+  set(IOS_DEPLOYMENT_TARGET "7.0")
+endif()
+set(IOS_DEPLOYMENT_TARGET ${IOS_DEPLOYMENT_TARGET} CACHE STRING "Minimum iOS version")
+
+# Whether to enable bitcode
+if(NOT DEFINED IOS_ENABLE_BITCODE)
+  set(IOS_ENABLE_BITCODE ON)
+endif()
+set(IOS_ENABLE_BITCODE ${IOS_ENABLE_BITCODE} CACHE BOOL "Whether to enable bitcode")
 
 # Check the platform selection and setup for developer root
-if (${IOS_PLATFORM} STREQUAL "OS")
-    set (IOS_PLATFORM_LOCATION "iPhoneOS.platform")
-    set (XCODE_IOS_PLATFORM iphoneos)
+if(${IOS_PLATFORM} STREQUAL "OS")
+  set(IOS_PLATFORM_LOCATION "iPhoneOS.platform")
+  set(XCODE_IOS_PLATFORM iphoneos)
 
   # This causes the installers to properly locate the output libraries
-    set (CMAKE_XCODE_EFFECTIVE_PLATFORMS "-iphoneos")
-elseif (${IOS_PLATFORM} STREQUAL "SIMULATOR")
-    set (SIMULATOR true)
-    set (IOS_PLATFORM_LOCATION "iPhoneSimulator.platform")
-    set (XCODE_IOS_PLATFORM iphonesimulator)
+  set(CMAKE_XCODE_EFFECTIVE_PLATFORMS "-iphoneos")
+elseif(${IOS_PLATFORM} STREQUAL "SIMULATOR")
+  set(IOS_PLATFORM_LOCATION "iPhoneSimulator.platform")
+  set(XCODE_IOS_PLATFORM iphonesimulator)
 
   # This causes the installers to properly locate the output libraries
-    set (CMAKE_XCODE_EFFECTIVE_PLATFORMS "-iphonesimulator")
-elseif (${IOS_PLATFORM} STREQUAL "WATCHOS")
-    set (IOS_PLATFORM_LOCATION "WatchOS.platform")
-    set (XCODE_IOS_PLATFORM watchos)
+  set(CMAKE_XCODE_EFFECTIVE_PLATFORMS "-iphonesimulator")
+elseif(${IOS_PLATFORM} STREQUAL "WATCHOS")
+  set(IOS_PLATFORM_LOCATION "WatchOS.platform")
+  set(XCODE_IOS_PLATFORM watchos)
 
   # This causes the installers to properly locate the output libraries
-    set (CMAKE_XCODE_EFFECTIVE_PLATFORMS "-watchos")
-else (${IOS_PLATFORM} STREQUAL "OS")
-    message (FATAL_ERROR
-             "Unsupported IOS_PLATFORM value selected. "
-             "Please choose OS, SIMULATOR, or WATCHOS.")
-endif ()
-
-# All iOS/Darwin specific settings - some may be redundant
-set (CMAKE_SHARED_LIBRARY_PREFIX "lib")
-set (CMAKE_SHARED_LIBRARY_SUFFIX ".dylib")
-set (CMAKE_SHARED_MODULE_PREFIX "lib")
-set (CMAKE_SHARED_MODULE_SUFFIX ".so")
-set (CMAKE_MODULE_EXISTS 1)
-set (CMAKE_DL_LIBS "")
-
-set (CMAKE_C_OSX_COMPATIBILITY_VERSION_FLAG "-compatibility_version ")
-set (CMAKE_C_OSX_CURRENT_VERSION_FLAG "-current_version ")
-set (CMAKE_CXX_OSX_COMPATIBILITY_VERSION_FLAG "${CMAKE_C_OSX_COMPATIBILITY_VERSION_FLAG}")
-set (CMAKE_CXX_OSX_CURRENT_VERSION_FLAG "${CMAKE_C_OSX_CURRENT_VERSION_FLAG}")
-
-if (IOS_DEPLOYMENT_TARGET)
+  set(CMAKE_XCODE_EFFECTIVE_PLATFORMS "-watchos")
+else(${IOS_PLATFORM} STREQUAL "OS")
+  message(FATAL_ERROR "Unsupported IOS_PLATFORM value selected. Please set to\n"
+          "\t OS, SIMULATOR, or WATCHOS.")
+endif()
+
+# Check iOS developer toolchain
+if(NOT DEFINED IOS_DEVELOPER_ROOT)
+  # Setup iOS developer location
+  execute_process(COMMAND xcode-select -print-path
+                  OUTPUT_VARIABLE XCODE_DEVELOPER_DIR
+                  RESULT_VARIABLE XCODE_DEVELOPER_DIR_RESULT
+                  ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE)
+  # Xcode 4.3 changed the installation location, choose the most recent one available
+  if(${XCODE_VERSION} VERSION_LESS "4.3.0")
+    set(IOS_DEVELOPER_ROOT "/Developer/Platforms/${IOS_PLATFORM_LOCATION}/Developer")
+  else()
+    set(IOS_DEVELOPER_ROOT "${XCODE_DEVELOPER_DIR}/Platforms/${IOS_PLATFORM_LOCATION}/Developer")
+  endif()
+endif()
+if(EXISTS ${IOS_DEVELOPER_ROOT})
+  set(IOS_DEVELOPER_ROOT ${IOS_DEVELOPER_ROOT} CACHE PATH "Location of iOS Platform")
+else()
+  message(FATAL_ERROR "Invalid IOS_DEVELOPER_ROOT: ${IOS_DEVELOPER_ROOT} does not exist.")
+endif()
+
+# Check iOS SDK
+if(NOT DEFINED IOS_SDK_ROOT)
+  # Find and use the most recent iOS sdk
+  file(GLOB IOS_SDK_LISTS "${IOS_DEVELOPER_ROOT}/SDKs/*")
+  if(IOS_SDK_LISTS)
+    list(SORT IOS_SDK_LISTS)
+    list(REVERSE IOS_SDK_LISTS)
+    list(GET IOS_SDK_LISTS 0 IOS_SDK_ROOT)
+  else(IOS_SDK_LISTS)
+    message(FATAL_ERROR "No iOS SDK's found in default search path ${IOS_DEVELOPER_ROOT}."
+            " Please manually set IOS_SDK_ROOT or install the iOS SDK.")
+  endif(IOS_SDK_LISTS)
+endif()
+if(EXISTS ${IOS_SDK_ROOT})
+  set(CMAKE_IOS_SDK_ROOT ${CMAKE_IOS_SDK_ROOT} CACHE PATH "Location of the selected iOS SDK")
+  message(STATUS "iOS toolchain: ${IOS_SDK_ROOT}")
+else()
+  message(FATAL_ERROR "Invalid IOS_SDK_ROOT: ${IOS_SDK_ROOT} does not exist.")
+endif()
+
+# Set the sysroot default to the most recent SDK
+set(CMAKE_OSX_SYSROOT ${IOS_SDK_ROOT} CACHE PATH "Sysroot used for iOS support")
+
+# Get version of iOS SDK
+execute_process(COMMAND xcodebuild -sdk ${CMAKE_OSX_SYSROOT} -version SDKVersion
+                OUTPUT_VARIABLE IOS_SDK_VERSION
+                RESULT_VARIABLE IOS_SDK_VERSION_RESULT
+                ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE)
+if(${IOS_SDK_VERSION_RESULT})
+  string(REGEX MATCH "(([0-9]+)\\.)+([0-9]+)" IOS_SDK_VERSION "${IOS_SDK_ROOT}")
+endif()
+if(NOT IOS_SDK_VERSION)
+  message(WARNING "Cannot get SDK's version.")
+  set(IOS_SDK_VERSION 1)
+endif()
+set(CMAKE_SYSTEM_VERSION ${IOS_SDK_VERSION})
+
+# Find the C & C++ compilers for the specified SDK.
+if(NOT CMAKE_C_COMPILER)
+  # Default to use clang
+  execute_process(COMMAND xcrun -sdk ${CMAKE_OSX_SYSROOT} -find clang
+                  OUTPUT_VARIABLE IOS_C_COMPILER
+                  RESULT_VARIABLE IOS_C_COMPILER_RESULT
+                  ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE)
+  if(${IOS_C_COMPILER_RESULT})
+    get_filename_component(IOS_C_COMPILER clang PROGRAM)
+  endif()
+else(NOT CMAKE_C_COMPILER)
+  # User can set it in cmake command
+  get_filename_component(IOS_C_COMPILER ${CMAKE_C_COMPILER} PROGRAM)
+endif(NOT CMAKE_C_COMPILER)
+if(NOT EXISTS ${IOS_C_COMPILER})
+  message(FATAL_ERROR "Cannot find C compiler: ${IOS_C_COMPILER}")
+endif()
+
+if(NOT CMAKE_CXX_COMPILER)
+  # Default to use clang++
+  execute_process(COMMAND xcrun -sdk ${CMAKE_OSX_SYSROOT} -find clang++
+                  OUTPUT_VARIABLE IOS_CXX_COMPILER
+                  RESULT_VARIABLE IOS_CXX_COMPILER_RESULT
+                  ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE)
+  if(${IOS_CXX_COMPILER_RESULT})
+    get_filename_component(IOS_CXX_COMPILER clang++ PROGRAM)
+  endif()
+else(NOT CMAKE_CXX_COMPILER)
+  # User can set it in cmake command
+  get_filename_component(IOS_CXX_COMPILER ${CMAKE_CXX_COMPILER} PROGRAM)
+endif(NOT CMAKE_CXX_COMPILER)
+if(NOT EXISTS ${IOS_CXX_COMPILER})
+  message(FATAL_ERROR "Cannot find CXX compiler: ${IOS_CXX_COMPILER}")
+endif()
+
+set(CMAKE_C_COMPILER ${IOS_C_COMPILER} CACHE PATH "C compiler" FORCE)
+set(CMAKE_CXX_COMPILER ${IOS_CXX_COMPILER} CACHE PATH "CXX compiler" FORCE)
+
+set(CMAKE_C_OSX_COMPATIBILITY_VERSION_FLAG "-compatibility_version ")
+set(CMAKE_C_OSX_CURRENT_VERSION_FLAG "-current_version ")
+set(CMAKE_CXX_OSX_COMPATIBILITY_VERSION_FLAG "${CMAKE_C_OSX_COMPATIBILITY_VERSION_FLAG}")
+set(CMAKE_CXX_OSX_CURRENT_VERSION_FLAG "${CMAKE_C_OSX_CURRENT_VERSION_FLAG}")
+
+# Set iOS specific C/C++ flags
+if(IOS_PLATFORM STREQUAL "OS")
+  if(XCODE_VERSION VERSION_LESS "7.0")
+    set(XCODE_IOS_PLATFORM_VERSION_FLAGS "-mios-version-min=${IOS_DEPLOYMENT_TARGET}")
+  else()
+    # Xcode 7.0+ uses flags we can build directly from XCODE_IOS_PLATFORM.
     set(XCODE_IOS_PLATFORM_VERSION_FLAGS "-m${XCODE_IOS_PLATFORM}-version-min=${IOS_DEPLOYMENT_TARGET}")
+  endif()
+else()
+  set(XCODE_IOS_FLATFORM_VERSION_FLAGS "-mios-simulator-version-min=${IOS_DEPLOYMENT_TARGET}")
+endif()
+
+if(IOS_ENABLE_BITCODE)
+  set(XCODE_IOS_BITCODE_FLAGS "${IOS_COMPILER_FLAGS} -fembed-bitcode")
+else()
+  set(XCODE_IOS_BITCODE_FLAGS "")
 endif()
 
+set(IOS_COMPILER_FLAGS "${XCODE_IOS_PLATFORM_VERSION_FLAGS} ${XCODE_IOS_BITCODE_FLAGS}")
+
 # Hidden visibilty is required for cxx on iOS 
-set (CMAKE_C_FLAGS_INIT "${XCODE_IOS_PLATFORM_VERSION_FLAGS}")
-set (CMAKE_CXX_FLAGS_INIT "${XCODE_IOS_PLATFORM_VERSION_FLAGS} -fvisibility-inlines-hidden")
+set(CMAKE_C_FLAGS "${IOS_COMPILER_FLAGS} ${CMAKE_C_FLAGS}" CACHE STRING "C flags")
+set(CMAKE_CXX_FLAGS "${IOS_COMPILER_FLAGS} -fvisibility-inlines-hidden ${CMAKE_CXX_FLAGS}" CACHE STRING "CXX flags")
 
-set (CMAKE_C_LINK_FLAGS "${XCODE_IOS_PLATFORM_VERSION_FLAGS} -Wl,-search_paths_first ${CMAKE_C_LINK_FLAGS}")
-set (CMAKE_CXX_LINK_FLAGS "${XCODE_IOS_PLATFORM_VERSION_FLAGS} -Wl,-search_paths_first ${CMAKE_CXX_LINK_FLAGS}")
+set(CMAKE_C_LINK_FLAGS "${XCODE_IOS_PLATFORM_VERSION_FLAGS} -Wl,-search_paths_first ${CMAKE_C_LINK_FLAGS}")
+set(CMAKE_CXX_LINK_FLAGS "${XCODE_IOS_PLATFORM_VERSION_FLAGS} -Wl,-search_paths_first ${CMAKE_CXX_LINK_FLAGS}")
 
-set (CMAKE_PLATFORM_HAS_INSTALLNAME 1)
-set (CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS "-dynamiclib -headerpad_max_install_names")
-set (CMAKE_SHARED_MODULE_CREATE_C_FLAGS "-bundle -headerpad_max_install_names")
-set (CMAKE_SHARED_MODULE_LOADER_C_FLAG "-Wl,-bundle_loader,")
-set (CMAKE_SHARED_MODULE_LOADER_CXX_FLAG "-Wl,-bundle_loader,")
-set (CMAKE_FIND_LIBRARY_SUFFIXES ".dylib" ".so" ".a")
+set(CMAKE_PLATFORM_HAS_INSTALLNAME 1)
+set(CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS "-dynamiclib -headerpad_max_install_names")
+set(CMAKE_SHARED_MODULE_CREATE_C_FLAGS "-bundle -headerpad_max_install_names")
+set(CMAKE_SHARED_MODULE_LOADER_C_FLAG "-Wl,-bundle_loader,")
+set(CMAKE_SHARED_MODULE_LOADER_CXX_FLAG "-Wl,-bundle_loader,")
+set(CMAKE_FIND_LIBRARY_SUFFIXES ".dylib" ".so" ".a")
 
 # hack: if a new cmake (which uses CMAKE_INSTALL_NAME_TOOL) runs on an old build tree
 # (where install_name_tool was hardcoded) and where CMAKE_INSTALL_NAME_TOOL isn't in the cache
 # and still cmake didn't fail in CMakeFindBinUtils.cmake (because it isn't rerun)
 # hardcode CMAKE_INSTALL_NAME_TOOL here to install_name_tool, so it behaves as it did before, Alex
-if (NOT DEFINED CMAKE_INSTALL_NAME_TOOL)
+if(NOT DEFINED CMAKE_INSTALL_NAME_TOOL)
   find_program(CMAKE_INSTALL_NAME_TOOL install_name_tool)
-endif (NOT DEFINED CMAKE_INSTALL_NAME_TOOL)
-
-# Setup iOS deployment target
-set (IOS_DEPLOYMENT_TARGET ${IOS_DEPLOYMENT_TARGET} CACHE STRING "Minimum iOS version")
-
-# Setup iOS developer location unless specified manually with CMAKE_IOS_DEVELOPER_ROOT
-# Note Xcode 4.3 changed the installation location, choose the most recent one available
-exec_program(/usr/bin/xcode-select ARGS -print-path OUTPUT_VARIABLE CMAKE_XCODE_DEVELOPER_DIR)
-set (XCODE_POST_43_ROOT "${CMAKE_XCODE_DEVELOPER_DIR}/Platforms/${IOS_PLATFORM_LOCATION}/Developer")
-set (XCODE_PRE_43_ROOT "/Developer/Platforms/${IOS_PLATFORM_LOCATION}/Developer")
-if (NOT DEFINED CMAKE_IOS_DEVELOPER_ROOT)
-    if (EXISTS ${XCODE_POST_43_ROOT})
-        set (CMAKE_IOS_DEVELOPER_ROOT ${XCODE_POST_43_ROOT})
-    elseif(EXISTS ${XCODE_PRE_43_ROOT})
-        set (CMAKE_IOS_DEVELOPER_ROOT ${XCODE_PRE_43_ROOT})
-    endif (EXISTS ${XCODE_POST_43_ROOT})
-endif (NOT DEFINED CMAKE_IOS_DEVELOPER_ROOT)
-set (CMAKE_IOS_DEVELOPER_ROOT ${CMAKE_IOS_DEVELOPER_ROOT} CACHE PATH "Location of iOS Platform")
-
-# Find and use the most recent iOS sdk unless specified manually with CMAKE_IOS_SDK_ROOT
-if (NOT DEFINED CMAKE_IOS_SDK_ROOT)
-    file (GLOB _CMAKE_IOS_SDKS "${CMAKE_IOS_DEVELOPER_ROOT}/SDKs/*")
-    if (_CMAKE_IOS_SDKS) 
-        list (SORT _CMAKE_IOS_SDKS)
-        list (REVERSE _CMAKE_IOS_SDKS)
-        list (GET _CMAKE_IOS_SDKS 0 CMAKE_IOS_SDK_ROOT)
-    else (_CMAKE_IOS_SDKS)
-        message (FATAL_ERROR "No iOS SDK's found in default search path ${CMAKE_IOS_DEVELOPER_ROOT}. Manually set CMAKE_IOS_SDK_ROOT or install the iOS SDK.")
-    endif (_CMAKE_IOS_SDKS)
-    message (STATUS "Toolchain using default iOS SDK: ${CMAKE_IOS_SDK_ROOT}")
-endif (NOT DEFINED CMAKE_IOS_SDK_ROOT)
-set (CMAKE_IOS_SDK_ROOT ${CMAKE_IOS_SDK_ROOT} CACHE PATH "Location of the selected iOS SDK")
-
-# Set the sysroot default to the most recent SDK
-set (CMAKE_OSX_SYSROOT ${CMAKE_IOS_SDK_ROOT} CACHE PATH "Sysroot used for iOS support")
-
-# set the architecture for iOS 
-if (IOS_PLATFORM STREQUAL "OS")
-    set (IOS_ARCH "armv7;armv7s;arm64")
-elseif (IOS_PLATFORM STREQUAL "SIMULATOR")
-    set (IOS_ARCH "i386;x86_64")
-elseif (IOS_PLATFORM STREQUAL "WATCHOS")
-    set (IOS_ARCH "armv7k")
-endif ()
-
-set (CMAKE_OSX_ARCHITECTURES ${IOS_ARCH} CACHE string  "Build architecture for iOS")
+endif()
 
 # Set the find root to the iOS developer roots and to user defined paths
-set (CMAKE_FIND_ROOT_PATH ${CMAKE_IOS_DEVELOPER_ROOT} ${CMAKE_IOS_SDK_ROOT} ${CMAKE_PREFIX_PATH} CACHE string  "iOS find search path root")
+set(CMAKE_FIND_ROOT_PATH ${IOS_DEVELOPER_ROOT} ${IOS_SDK_ROOT} ${CMAKE_PREFIX_PATH}
+    CACHE string  "iOS find search path root")
 
 # default to searching for frameworks first
-set (CMAKE_FIND_FRAMEWORK FIRST)
+set(CMAKE_FIND_FRAMEWORK FIRST)
 
 # set up the default search directories for frameworks
-set (CMAKE_SYSTEM_FRAMEWORK_PATH
-    ${CMAKE_IOS_SDK_ROOT}/System/Library/Frameworks
-    ${CMAKE_IOS_SDK_ROOT}/System/Library/PrivateFrameworks
-    ${CMAKE_IOS_SDK_ROOT}/Developer/Library/Frameworks
-)
+set(CMAKE_SYSTEM_FRAMEWORK_PATH
+    ${IOS_SDK_ROOT}/System/Library/Frameworks
+    ${IOS_SDK_ROOT}/System/Library/PrivateFrameworks
+    ${IOS_SDK_ROOT}/Developer/Library/Frameworks
+    )
 
 # only search the iOS sdks, not the remainder of the host filesystem
-set (CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
-set (CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
-set (CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+
+message(STATUS "iOS: Targeting iOS '${CMAKE_SYSTEM_VERSION}', "
+        "building for '${IOS_PLATFORM}' platform, with architecture '${CMAKE_OSX_ARCHITECTURES}'")
 
 # This little macro lets you set any XCode specific property
-macro (set_xcode_property TARGET XCODE_PROPERTY XCODE_VALUE)
+macro(set_xcode_property TARGET XCODE_PROPERTY XCODE_VALUE)
   set_property (TARGET ${TARGET} PROPERTY XCODE_ATTRIBUTE_${XCODE_PROPERTY} ${XCODE_VALUE})
-endmacro (set_xcode_property)
+endmacro(set_xcode_property)
 
 # This macro lets you find executable programs on the host system
-macro (find_host_package)
-    set (CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
-    set (CMAKE_FIND_ROOT_PATH_MODE_LIBRARY NEVER)
-    set (CMAKE_FIND_ROOT_PATH_MODE_INCLUDE NEVER)
-    set (IOS FALSE)
+macro(find_host_package)
+  set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+  set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY NEVER)
+  set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE NEVER)
+  set(IOS FALSE)
 
   find_package(${ARGN})
 
-    set (IOS TRUE)
-    set (CMAKE_FIND_ROOT_PATH_MODE_PROGRAM ONLY)
-    set (CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
-    set (CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
-endmacro (find_host_package)
+  set(IOS TRUE)
+  set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM ONLY)
+  set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+  set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+endmacro(find_host_package)

cmake/flags.cmake

@@ -135,8 +135,10 @@ set(GPU_COMMON_FLAGS
 )
 
 if (APPLE)
+    if(NOT CMAKE_CROSSCOMPILING)
         # On Mac OS X build fat binaries with x86_64 architectures by default.
         set (CMAKE_OSX_ARCHITECTURES "x86_64" CACHE STRING "Build architectures for OSX" FORCE)
+    endif()
 else()
     set(GPU_COMMON_FLAGS
         -Wall

cmake/system.cmake

@@ -24,11 +24,10 @@ IF(WIN32)
     SET(HOST_SYSTEM "win32")
 ELSE(WIN32)
     IF(APPLE)
-        EXEC_PROGRAM (sw_vers ARGS -productVersion OUTPUT_VARIABLE MACOSX_VERSION)
-        STRING(REGEX MATCH "[0-9]+.[0-9]+" VERSION "${MACOSX_VERSION}")
-        SET(MACOS_VERSION ${VERSION})
         SET(HOST_SYSTEM "macosx")
-        IF(NOT DEFINED ENV{MACOSX_DEPLOYMENT_TARGET})
+        EXEC_PROGRAM(sw_vers ARGS -productVersion OUTPUT_VARIABLE HOST_SYSTEM_VERSION)
+        STRING(REGEX MATCH "[0-9]+.[0-9]+" MACOS_VERSION "${HOST_SYSTEM_VERSION}")
+        IF(NOT DEFINED $ENV{MACOSX_DEPLOYMENT_TARGET})
             # Set cache variable - end user may change this during ccmake or cmake-gui configure.
             SET(CMAKE_OSX_DEPLOYMENT_TARGET ${MACOS_VERSION} CACHE STRING
                 "Minimum OS X version to target for deployment (at runtime); newer APIs weak linked. Set to empty string for default value.")
@@ -49,6 +48,8 @@ ELSE(WIN32)
             ELSEIF(LINUX_ISSUE MATCHES "Fedora")
                 SET(HOST_SYSTEM "fedora")
             ENDIF()
+
+            STRING(REGEX MATCH "(([0-9]+)\\.)+([0-9]+)" HOST_SYSTEM_VERSION "${LINUX_ISSUE}")
         ENDIF(EXISTS "/etc/issue")
 
         IF(EXISTS "/etc/redhat-release")
@@ -70,7 +71,7 @@ CMAKE_HOST_SYSTEM_INFORMATION(RESULT CPU_CORES QUERY NUMBER_OF_LOGICAL_CORES)
 
 MARK_AS_ADVANCED(HOST_SYSTEM CPU_CORES)
 
-MESSAGE(STATUS "Found Paddle host system: ${HOST_SYSTEM}")
+MESSAGE(STATUS "Found Paddle host system: ${HOST_SYSTEM}, version: ${HOST_SYSTEM_VERSION}")
 MESSAGE(STATUS "Found Paddle host system's CPU: ${CPU_CORES} cores")
 
 # configuration for cross-compiling
@@ -82,7 +83,7 @@ IF(DEFINED CMAKE_SYSTEM_NAME)
     ELSEIF(${CMAKE_SYSTEM_NAME} STREQUAL "RPi")
         SET(RPI TRUE)
         INCLUDE(cross_compiling/raspberry_pi)
-    ELSEIF(${CMAKE_SYSTEM_NAME} STREQUAL "Darwin")
+    ELSEIF(${CMAKE_SYSTEM_NAME} STREQUAL "iOS")
         SET(IOS TRUE)
         INCLUDE(cross_compiling/ios)
     ENDIF()