Building SRT for iOS

Prerequisites

• Xcode should be installed. Check in terminal whether xcode-select -p points to /Applications/Xcode.app/Contents/Developer
• Install Homebrew according to instructions on https://brew.sh/
• Install CMake and pkg-config with Homebrew:

brew install cmake
brew install pkg-config

Building OpenSSL

There is OpenSSL for iPhone project which have all necessary to build OpenSSL for our needs. It fetches OpenSSL code by itself, so you don’t need to download it separately. So simply clone it and build with command:

./build-libssl.sh --archs="arm64"

Results (both libraries and headers) will be placed in bin/<SDK_VERSION>-<ARCH>.sdk directory (for example, bin/iPhoneOS11.2-arm64.sdk). We assume you set IOS_OPENSSL variable to this path (e.g. export IOS_OPENSSL="/Users/johndoe/sources/OpenSSL-for-iPhone/bin/iPhoneOS11.2-arm64.sdk").

위와 같이 했음에도 OPENSSL 위치를 제대로 찾지 못하고 Makefile이 제대로 생성되지 않아서 아래 3가지 변수에 직접 iPhone용으로 build된 OpensSSL 경로를 직접 지정해 주었다.

export IOS_OPENSSL=”/Users/johndoe/sources/OpenSSL-for-iPhone/bin/iPhoneOS11.2-arm64.sdk”

export LDFLAGS=”-L/Users/byungchenmoon/Source/OpenSSL-for-iPhone/bin/iPhoneOS12.1-arm64.sdk/lib”

export CPPFLAGS=”-I/Users/byungchenmoon/Source/OpenSSL-for-iPhone/bin/iPhoneOS12.1-arm64.sdk/include”

export PKG_CONFIG_PATH=”/Users/byungchenmoon/Source/OpenSSL-for-iPhone/bin/iPhoneOS12.1-arm64.sdk/lib/pkgconfig”

Building SRT code

Now you can build SRT providing path to OpenSSL library and toolchain file for iOS

./configure --cmake-prefix-path=$IOS_OPENSSL --cmake-toolchain-file=scripts/iOS.cmake
make

Optionally you may add following iOS-specifc settings to configure:

• --ios-disable-bitcode=1 – disable embedding bitcode to library.
• --ios-arch=armv7|armv7s|arm64 – specify if you want to build for specific architecture (arm64 by default)
• --ios-platform=OS|SIMULATOR|SIMULATOR64 – specify for build simulator code
• --cmake-ios-developer-root=<path>– specify path for platform directory; {XCODE_ROOT}/Platforms/iPhoneOS.platform/Developer by default
• --cmake-ios-sdk-root=<path> – by default searches for latest SDK version within {CMAKE_IOS_DEVELOPER_ROOT}/SDKs, set if you want to use another SDK version

Note that resulting .dylib file has install path @executable_path/Frameworks/libsrt.1.dylib, so if you need to place it in some other place with your application, you may change it with install_name_tool command: install_name_tool -id "<install_path>" <library_file>, for example install_name_tool -id "@executable_path/Frameworks/libsrt.1.3.0.dylib" libsrt.1.3.0.dylib

Adding to Xcode project

In Xcode project settings in General tab, add libsrt to Linked Frameworks and Libraries section – click Plus sign, then click “Add Other” and find libsrt.1.dylib

Click plus sign in Embedded binaries section and choose Frameworks/libsrt.1.dylib

In Build settings tab find Header Search Paths setting
and add paths to SRT library sources (you should add srt, srt/common and srt/common directories).