Set up an Objective-C 2.0 development environment on Linux

It's been a long time since the trend moved to Swift, and the number of people who are interested in Objective-C has decreased in recent years, but here is a summary of how to set up an Objective-C development environment on Linux.

We have confirmed the operation on Ubuntu 18.04 and 19.10 on Docker. If you extract the contents of ʻENVandRUN` in the Dockerfile, it will work on the actual machine.

If Objective-C 1.0 is fine ...

If you're happy with the old-fashioned Objective-C 1.0, you can set up an Objective-C development environment with Clang 9 relatively easily by installing a ready-made package available with apt.

Dockerfile

FROM ubuntu:19.10

RUN set -x \
  && apt update \
  && apt upgrade -y \
  && DEBIAN_FRONTEND=noninteractive apt install -y tzdata \
  && apt install -y clang-9 make gobjc-9 gnustep-devel \
  && apt autoremove -y \
  && apt clean \
  && rm -rf /var/cache/apt/archives/* /var/lib/apt/lists/*

# Set alias
RUN echo 'alias clang-objc="clang-9 \$(gnustep-config --objc-flags) \$(gnustep-config --objc-libs) -lgnustep-base -I/usr/lib/gcc/x86_64-linux-gnu/9/include"' > ~/.bashrc

CMD ["/bin/bash"]

The essence is

$ apt install -y clang-9 make gobjc-9 gnustep-devel

is. Also, in ~ / .bashrc

alias clang-objc="clang-9 \$(gnustep-config --objc-flags) \$(gnustep-config --objc-libs) -lgnustep-base -I/usr/lib/gcc/x86_64-linux-gnu/9/include"

It is defined as. This will allow you to do this within this Docker container

$ clang-objc -o hoge hoge.m
$ ./hoge

You can easily compile and execute the Objective-C source hoge.m by doing so.

If you want to use the full functionality of Objective-C 2.0 ...

• Automatic Reference Counting (ARC)
• Blocks
• Dot Notation
• Object Literal
• Object Subscripting
• Fast Enumeration
• Lightweight Generics
• Grand Central Dispatch (GCD)

If you want to take full advantage of Modern Objective-C features like, you have to set up libobjc2 in GNUstep. It cannot be installed with apt, so you need to build it from source. This is quite difficult. plaurent's GitHub repository was very helpful. The build procedure can be summarized in a Dockerfile as follows.

Dockerfile

FROM ubuntu:19.10

ENV CC clang-9
ENV CXX clang++-9
ENV CXXFLAGS -std=c++11
ENV RUNTIME_VERSION gnustep-2.0
ENV PKG_CONFIG_PATH /usr/local/lib/pkgconfig
ENV LD /usr/bin/ld.gold
ENV LDFLAGS "-fuse-ld=/usr/bin/ld.gold -L/usr/local/lib"

WORKDIR /GNUstep-build

RUN set -x \
  && apt update \
  && apt upgrade -y \
  && apt install -y git sudo clang-9 clang++-9 build-essential wget \
    subversion cmake libffi-dev libxml2-dev \
    libgnutls28-dev libicu-dev libblocksruntime-dev libkqueue-dev libpthread-workqueue-dev autoconf libtool \
    libjpeg-dev libtiff-dev libffi-dev libcairo-dev libx11-dev libxt-dev libxft-dev \
  && apt autoremove -y \
  && apt clean \
  && rm -rf /var/cache/apt/archives/* /var/lib/apt/lists/*

# Build GNUstep make
RUN set -x \
    #
    # Checkout tools-make
    && git clone https://github.com/gnustep/tools-make.git \
    #
    # Build GNUstep make
    && cd tools-make \
    && CC=${CC} ./configure \
            --with-layout=gnustep \
            --disable-importing-config-file \
            --enable-native-objc-exceptions \
            --enable-objc-arc \
            --enable-install-ld-so-conf \
            --with-library-combo=ng-gnu-gnu \
    && make -j8 \
    && sudo -E make install \
    && . /usr/GNUstep/System/Library/Makefiles/GNUstep.sh \
    && echo ". /usr/GNUstep/System/Library/Makefiles/GNUstep.sh" >> ~/.bashrc \
    && echo "export RUNTIME_VERSION=gnustep-2.0" >> ~/.bashrc \
    && echo 'export CXXFLAGS="-std=c++11"' >> ~/.bashrc \
    && cd .. \
#
# Build libdispatch
    #
    # Checkout swift-corelibs-libdispatch
    && git clone https://github.com/apple/swift-corelibs-libdispatch \
    && cd swift-corelibs-libdispatch \
    && git checkout swift-5.1.1-RELEASE \
    #
    # Build libdispatch
    && rm -Rf build \
    && mkdir build \
    && cd build \
    && cmake .. \
         -DCMAKE_C_COMPILER=${CC} \
         -DCMAKE_CXX_COMPILER=${CXX} \
         -DCMAKE_BUILD_TYPE=Release \
         -DUSE_GOLD_LINKER=YES \
    && make \
    && sudo -E make install \
    && sudo ldconfig \
    && cd ../.. \
#
# Build libobjc2
    #
    # Checkout libobjc2
    && git clone https://github.com/gnustep/libobjc2.git \
    && cd libobjc2 \
    && git submodule init \
    && git submodule sync \
    && git submodule update \
    #
    # Build libobjc2
    && rm -Rf build \
    && mkdir build \
    && cd build \
    && cmake .. \
         -DCMAKE_C_COMPILER=${CC} \
         -DCMAKE_CXX_COMPILER=${CXX} \
         -DCMAKE_ASM_COMPILER=${CC} \
         -DTESTS=OFF \
    && cmake --build . \
    && sudo -E make install \
    && sudo ldconfig \
    && cd ../.. \
#
# Build GNUstep make second time
    && cd tools-make \
    && CC=${CC} ./configure \
            --with-layout=gnustep \
            --disable-importing-config-file \
            --enable-native-objc-exceptions \
            --enable-objc-arc \
            --enable-install-ld-so-conf \
            --with-library-combo=ng-gnu-gnu \
    && make -j8 \
    && sudo -E make install \
    && . /usr/GNUstep/System/Library/Makefiles/GNUstep.sh \
    && cd .. \
#
# Build GNUstep base
    #
    # Checkout libs-base
    && git clone https://github.com/gnustep/libs-base.git \
    #
    # Build GNUstep base
    && cd libs-base \
    && ./configure \
    && make -j8 \
    && sudo -E make install \
    && cd .. 

# For GUI programming
#
# Build GNUstep GUI Library
RUN set -x \
    && . /usr/GNUstep/System/Library/Makefiles/GNUstep.sh \
    #
    # Checkout libs-gui
    && git clone https://github.com/gnustep/libs-gui.git \
    #
    # Build GNUstep GUI Library
    && cd libs-gui \
    && ./configure \
    && make -j8 \
    && sudo -E make install \
    && cd .. \
#
# Build GNUstep GUI Backend
    #
    # Checkout libs-back
    && git clone https://github.com/gnustep/libs-back.git \
    #
    # Build GNUstep GUI Backend
    && cd libs-back \
    && ./configure \
    && make -j8 \
    && sudo -E make install \
    && cd ..

WORKDIR /workdir

# Clean build directory
RUN rm -rf /GNUstep-build

# Set alias
RUN echo 'alias clang-objc="\${CC} \$(gnustep-config --objc-flags) \$(gnustep-config --objc-libs) -fobjc-arc -lobjc -ldispatch -lgnustep-base"' >> ~/.bashrc

CMD ["/bin/bash"]

It was a long build procedure ... Finally to ~ / .bashrc

alias clang-objc="\${CC} \$(gnustep-config --objc-flags) \$(gnustep-config --objc-libs) -fobjc-arc -lobjc -ldispatch -lgnustep-base"

Is set, so in this Docker container

$ clang-objc -o hoge hoge.m
$ ./hoge

You can easily compile and run the Objective-C 2.0 source hoge.m by doing so.

Dockerfile and set of test files

The Dockerfile created this time and the set of Objective-C sources for testing have been uploaded to the GitHub repository.

$ docker run --rm -it -v $(pwd):/workdir doratex/clang9-objc2:latest /bin/bash
# cd test
# ./test_all.sh

You can test various Objective-C 2.0 features with. (However, the last GUI test of the tests will not work unless it is connected to the X Window System server.)

Docker image

The Docker image created this time is uploaded to Docker Hub repository.

$ docker pull doratex/clang9-objc2:ubuntu1910

You can use it if you do.