libevent for iOS about libevent

[Coeur]

I was able to build it for iOS and visionOS easily.

1. Make for Xcode without OpenSSL: cmake -B build -G Xcode -DEVENT__DISABLE_OPENSSL=ON
2. Open the resulting xcodeproj: open build/libevent.xcodeproj
3. Change Project's SDKROOT to iOS or visionOS
4. Build the "event_static" scheme for "Any iOS Device" or "Any visionOS Device"

[widgetii]

Hi, what's the difference between iOS and other platforms static libraries?

[palfonsoilluscio]

iOS and macOS for instance, have different SDK versions, which may result in differences in available APIs and features. But in general, while iOS and macOS static libraries share many similarities, differences in architecture, SDK versions, deployment targets, and app distribution requirements may need some adjustments when developing and using static libraries for each platform.

We can probably implement this for at least iOS by using:

/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -target arm64-apple-ios17.4 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS17.4.sdk -fembed-bitcode-marker -c -I /path/to/headers src/file_to_compile.c -o output_dir/compiled_file.o

But, if you have a better way to do so, happy to implement it...

Thanks in advance.

[palfonsoilluscio]

This is the initial error we are having, before doing anything:

ld: building for 'iOS', but linking in object file (/Users/xxx/Documents/Workspace/xxx/xxx/Frameworks/libevent.a[8](event.o)) built for 'macOS'
clang: error: linker command failed with exit code 1 (use -v to see invocation)

[palfonsoilluscio]

If you have maybe a CI script that we can check and help us to build for iOS, that would be great...

Thanks in advance.

[azat]

ld: building for 'iOS', but linking in object file (/Users/xxx/Documents/Workspace/xxx/xxx/Frameworks/libevent.a8) built for 'macOS'

Looks like some issue in your cross compilation

If you have maybe a CI script that we can check and help us to build for iOS, that would be great...

We only have CI for MacOS -

libevent/.github/workflows/build.yml

Lines 527 to 619 in a942694

	macos-cmake-job:
	runs-on: ${{ matrix.os }}
	if: "!contains(github.event.head_commit.message, 'ci/macos skip') && !contains(github.event.head_commit.message, 'ci/macos/cmake skip')"
	strategy:
	fail-fast: false
	matrix:
	os: [macos-latest]
	EVENT_MATRIX:
	- NONE
	- NO_SSL
	- DISABLE_OPENSSL
	- DISABLE_THREAD_SUPPORT
	- DISABLE_DEBUG_MODE
	- DISABLE_MM_REPLACEMENT
	- TEST_EXPORT_STATIC
	- TEST_EXPORT_SHARED
	steps:
	- uses: actions/checkout@v3
	- name: Cache Build
	uses: actions/cache@v4
	with:
	path: build
	key: ${{ matrix.os }}-cmake-${{ matrix.EVENT_MATRIX }}-v3
	- name: Install Depends
	run: brew install mbedtls@2
	- name: Build
	shell: bash
	run: |
	# NOTE: cmake does not support autodetection of OPENSSL_ROOT_DIR via brew
	export OPENSSL_ROOT_DIR=/usr/local/opt/openssl
	if [ "${{ matrix.EVENT_MATRIX }}" == "DISABLE_OPENSSL" ]; then
	EVENT_CMAKE_OPTIONS="-DEVENT__DISABLE_OPENSSL=ON"
	elif [ "${{ matrix.EVENT_MATRIX }}" == "NO_SSL" ]; then
	EVENT_CMAKE_OPTIONS="-DEVENT__DISABLE_OPENSSL=ON -DEVENT__DISABLE_MBEDTLS=ON"
	elif [ "${{ matrix.EVENT_MATRIX }}" == "DISABLE_THREAD_SUPPORT" ]; then
	EVENT_CMAKE_OPTIONS="-DEVENT__DISABLE_THREAD_SUPPORT=ON"
	elif [ "${{ matrix.EVENT_MATRIX }}" == "DISABLE_DEBUG_MODE" ]; then
	EVENT_CMAKE_OPTIONS="-DEVENT__DISABLE_DEBUG_MODE=ON"
	elif [ "${{ matrix.EVENT_MATRIX }}" == "DISABLE_MM_REPLACEMENT" ]; then
	EVENT_CMAKE_OPTIONS="-DEVENT__DISABLE_MM_REPLACEMENT=ON"
	elif [ "${{ matrix.EVENT_MATRIX }}" == "TEST_EXPORT_STATIC" ]; then
	EVENT_CMAKE_OPTIONS="-DEVENT__LIBRARY_TYPE=STATIC -DEVENT__DISABLE_TESTS=ON -DEVENT__DISABLE_SAMPLES=ON"
	elif [ "${{ matrix.EVENT_MATRIX }}" == "TEST_EXPORT_SHARED" ]; then
	EVENT_CMAKE_OPTIONS="-DEVENT__LIBRARY_TYPE=SHARED -DEVENT__DISABLE_TESTS=ON -DEVENT__DISABLE_SAMPLES=ON"
	else
	EVENT_CMAKE_OPTIONS=""
	fi
	EVENT_CMAKE_OPTIONS="$EVENT_CMAKE_OPTIONS -DMBEDTLS_ROOT_DIR=/usr/local/opt/mbedtls@2"
	mkdir -p build
	cd build
	echo [cmake]: cmake .. $EVENT_CMAKE_OPTIONS
	cmake .. $EVENT_CMAKE_OPTIONS || (rm -rf * && cmake .. $EVENT_CMAKE_OPTIONS)
	cmake --build .
	- name: Test
	uses: nick-fields/retry@v3
	with:
	max_attempts: 5
	timeout_minutes: 60
	shell: bash
	command: |
	JOBS=1
	export CTEST_PARALLEL_LEVEL=$JOBS
	export CTEST_OUTPUT_ON_FAILURE=1
	cd build
	if [ "${{ matrix.EVENT_MATRIX }}" == "TEST_EXPORT_STATIC" ]; then
	sudo python3 ../test-export/test-export.py static
	elif [ "${{ matrix.EVENT_MATRIX }}" == "TEST_EXPORT_SHARED" ]; then
	sudo python3 ../test-export/test-export.py shared
	else
	cmake --build . --target verify
	fi
	- uses: actions/upload-artifact@v1
	if: failure()
	with:
	name: ${{ matrix.os }}-cmake-${{ matrix.EVENT_MATRIX }}-build
	path: build

[pedroalfonsoo]

Looks like some issue in your cross compilation ----> Correct, that's exactly what is happening because we are not able to get a libevent build for iOS.

We hoped we could get that from your team, is that possible or we just need look for another options?

Sorry just trying to understand the next steps.

[Coeur]

Oh, even simpler:

For iOS

cmake -B build -G Xcode -D CMAKE_OSX_SYSROOT=iphoneos
cmake --build build -t event_static

For visionOS

cmake -B build -G Xcode -D CMAKE_OSX_SYSROOT=xros
cmake --build build -t event_static

That's all. No need to disable openssl explicitly, no need to open Xcode : all is automatic and from command-line. Product will be in built in build/lib/Debug/libevent.a.