ROS2 on iOS and macOS

Build ROS2 stack for iOS software development.

This valuable experience allows us to build and run ROS2 on Mac including graphical tools such as RVIZ as well (see below).

For the impatient: Instead of building ROS2 from source (see below), you can download our prebuilt libs and extract it. Then make a symlink ros2 pointing to the extracted ros2_$PLATFORM where we can find the ROS2 lib and include headers

ln -s PATH_TO_EXTRACTED_ros2_$PLATFORM ros2

You should of course change the symlink target when switching between building for real iPhone, simulator and Mac Catalyst. Now we can run the demo application which ports the official example: Run the app on two simulator instances, click on Start publishing on one and Start listening on the other.

Note: To run Mac Catalyst app on your macOS machine, you need to sign the app with your development signing certificate.

Main guides:

• Build ROS2 from source on macOS
• Cross compiling ROS2
• ROS2 Architecture

Tools preparation

We are going to need

• CMake 3.23 until this issue is sorted out
• Python 3.11
• Xcode + Command Line tools

installed.

If you have other environment management such as Anaconda, remember to DEACTIVATE them. Then create and activate a Python virtual environment for ease of package installation

python3 -m venv ros2PythonEnv
source ros2PythonEnv/bin/activate
python3 -m pip install -r requirements.txt

Build ROS2 core communication packages for iOS

To build for iOS simulator on Intel Macs, use the script build_ros2.sh. You might need to change some variable in the script to match your system. Activate your Python environment then execute

 # change iOS to iOS_Simulator if you want to test ROS2 on the iPhone simulator
source build_ros2.sh iOS

buildRos2Base

at the root of this repo (the script must be sourced there so you should clone this repo where you want to put your ROS2 installation).

The key command in the script is

colcon build --merge-install \
    --cmake-force-configure \
    --cmake-args \
        -DCMAKE_TOOLCHAIN_FILE=$REPO_ROOT/cmake/iOS.cmake \
        -DBUILD_TESTING=NO \
        -DTHIRDPARTY=FORCE \
        -DCOMPILE_TOOLS=NO \
        -DBUILD_MEMORY_TOOLS=OFF \
        -DRCL_LOGGING_IMPLEMENTATION=rcl_logging_noop

After my tons of failures, here is what went going on behind the above command:

1. The classical method to CMake for iOS simulator in my other projects such as LibGit2 is to set the appropriate CMAKE_OSX_SYSROOT and CMAKE_OSX_ARCHITECTURES.

   Note: The right way to get clang to compile for iOS simulator is to set to CMAKE_C_FLAGS and CMAKE_CXX_FLAGS, namely -target x86_64-apple-ios-simulator -mios-version-min=14.0 together with -isysroot to find the standard headers.

   However, that is not going to work here. The reason is because of the ***_vendor packages which are proxy packages for 3rd party libraries such as libyaml: their CMake files fetch the library and passing to their CMake with the "right" options. Checking for example libyaml_vendor/CMakeLists.txt reveals that it does NOT pass along all our CMAKE_*** options except for CMAKE_C_FLAGS and even force BUILD_SHARED_LIBS=ON. We need to pass along all desired options in -DCMAKE_TOOLCHAIN_FILE and in that file, we set up all the desired CMake variables.

   Note: Even this is not going to be enough for some package such as mimick_vendor as it sets its internal variable _ARCH BEFORE considering the toolchain file!

2. BUILD_TESTING=NO to disable all test packages, without this, we are going to need a ton of third party packages such as ament/google_benchmark_vendor, ament/uncrustify_vendor, ament/googletest, osrf/osrf_testing_tools_cpp, ros2/performance_test_fixture and ros2/mimick_vendor and account for a ton of CMake issues

3. THIRDPARTY=FORCE is to ask eProsima Fast-DDS to build and use its own dependencies (asio, ...) so that we do not have to install it to the system with Homebrew

4. COMPILE_TOOLS=NO for Fast-DDS to NOT compile the fast discovery server executable.

5. BUILD_MEMORY_TOOLS=OFF is for foonathan_memory to disable building nodesize_db program

6. RCL_LOGGING_IMPLEMENTATION=rcl_logging_noop is to select the logging backend for rcl_logging. Here, I am using noop one to avoid one more dependency spdlog_vendor.

7. ROS2 depends significantly on dynamic linking. Do NOT add BUILD_SHARED_LIBS=NO, contrary to my other project LLVM where building static libs is needed!

Build ROS2 with graphical tools for macOS

While there is an option, namely RoboStack, to install ROS2 for macOS without having to build it from source, their prebuilt graphical tools such as rviz2 and gazebo do not work.

So I find a way to build ROS2 from source to use on macOS (Intel only) as well. There is no need to disable SIP like the official instruction suggested. I also build pretty much all dependencies so Homebrew isn't needed either.

Unlike iOS, you first need to build the dependencies using build_deps.sh and install XQuartz if you want to build MoveIt2. Then similar to iOS,

source build_ros2.sh macOS

buildRos2Base
buildRviz2       # Run if you need Rviz2 (depends on base)
buildMoveIt2     # Run if you need MoveIt2 (depends on Rviz2)

See build_ros2.sh for more details.

Using our prebuilt ROS2 for macOS

If you want to save yourself one full working day, you can use our release built using GitHub Action.

Note: We did not manage to build native ROS2 for ARM64 Mac but you can still use the Intel version thank to Rosetta 2. In that case, you will need to install x86_64 version of Python.

• If you download the file from a browser, it will be put in quarantine so you need to xattr -d com.apple.quarantine DOWNLOADED_FILE before extraction.
• To avoid that, you could open the terminal and do

  baseUrl=https://github.com/light-tech/ROS2-On-iOS/releases/download/humble-1.4
  curl -OL $baseUrl/deps_macOS.tar.xz \
       -O $baseUrl/base_macOS.tar.xz \
       -O $baseUrl/rviz2_macOS.tar.xz \
       -O $baseUrl/moveit2_macOS.tar.xz \
       -O $baseUrl/tutorials_macOS.tar.xz

  instead.

After extracting the archives with tar xzf and move the resulting ros2_macOS to where you want (I usually rename it to ros2 and move it inside ~/usr in my home folder along with the other Linux-based software), you need to fix hardcoded paths to match YOUR system as colcon (or maybe CMake) unfortunately hardcoded a lot of paths (mostly concerning Python-based stuffs) in generated files such as CMake and package config files.

• To do that, run our script fix_hardcoded_paths.sh and you will be prompted with the relevant information.
• The script is not exhaustive so you will need to manually fix the path such as the path to python3 in bin/ros2 so you can run ros2 command line such as ros2 launch and ros2 topic list.

Next, add this to your .zshrc (appropriate modification required)

activateROS2() {
    # So that ros2 can find the Python framework that you installed yourself.
    # Change the path /Library/Frameworks appropriately to fit your system.
    export DYLD_FRAMEWORK_PATH=/Library/Frameworks:$DYLD_FRAMEWORK_PATH

    source PATH_TO_PYTHON_ENV/bin/activate
    source PATH_TO_EXTRACTED_ROS2/moveit2/setup.zsh

    # Add the location for ROS2 to find prebuilt dependencies
    # Do this AFTER source setup.zsh because of https://github.com/colcon/colcon-zsh/issues/12
    export DYLD_LIBRARY_PATH=PATH_TO_EXTRACTED_ROS2/deps/lib:$DYLD_LIBRARY_PATH
}

so that anytime you need ROS2, you can simply execute activateROS2 in the terminal.

Now you can start using ROS2 as usual.

• Try following the various tutorials such as the image transport tutorial and the URDF tutorial.

ROS Development Tip

Define functions buildCMake and buildColcon in your .zshrc such as

buildCMake() {
    mkdir _build && cd _build
    cmake -DCMAKE_INSTALL_PREFIX=$HOME/usr/ros2/deps -DCMAKE_PREFIX_PATH="$HOME/usr/ros2/deps" "$@" ..
    cmake --build . --config Release --target install
}

buildColcon() {
    colcon build --symlink-install --cmake-args -DCMAKE_PREFIX_PATH=$PATH_TO_EXTRACTED_ROS2/deps -DBUILD_TESTING=NO
}

to avoid typing (copying and pasting) long chains of shell commands in the terminal.