本文描述的是macOS下编译webRTC frmework的过程及编译过程中遇到的问题，并提供解决方案

步骤

1. 安装depot_tools，配置环境变量

   git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
   export PATH=$PATH:/Users/suntongmian/Documents/develop/webrtc/depot_tools
   

2. 下载WebRTC源码

   #cd 到希望放置源代码的目录 执行以下命令
   fetch --nohooks webrtc_ios
   #执行完毕上面命令后
   gclient sync
   

3. 编译WebRTC

   gn gen out/ios --args='target_os="ios" target_cpu="arm64" is_debug=true'
   ninja -C out/ios framework_objc
   或
   gn gen out/ios --args='target_os="ios" target_cpu="arm64" is_debug=true'
   python tools_webrtc/ios/build_ios_libs.py --bitcode
   
   #执行完毕后可以在src/out/ios目录中看到生成的项目工程
   

问题记录

1. Exception: No 10.12+ SDK found

Traceback (most recent call last):

File "/Users/zhouyongchao/Documents/WorkingSpaces/webrtc_build/webrtc/src/build/mac/find_sdk.py", line 127, in <module>

print(main())

File "/Users/zhouyongchao/Documents/WorkingSpaces/webrtc_build/webrtc/src/build/mac/find_sdk.py", line 96, in main

raise Exception('No %s+ SDK found' % min_sdk_version)

Exception: No 10.12+ SDK found

解决方案:

1. 通过命令xcrun --show-sdk-version可以知道当前SDK的版本
2. 修改.gn文件的mac_sdk_min选项为当前系统版本：如：11.0
3. 打开find_sdk.py阅读代码发现了只支持10.xx的系统，修改11即可

2. LASTCHANGE.committime

Traceback (most recent call last):

File "/Users/zhouyongchao/Documents/WorkingSpaces/webrtc_build/webrtc/src/build/compute_build_timestamp.py", line 127, in <module>

sys.exit(main())

File "/Users/zhouyongchao/Documents/WorkingSpaces/webrtc_build/webrtc/src/build/compute_build_timestamp.py", line 113, in main

last_commit_timestamp = int(open(lastchange_file).read())

IOError: [Errno 2] No such file or directory: '/Users/zhouyongchao/Documents/WorkingSpaces/webrtc_build/webrtc/src/build/util/LASTCHANGE.committime'

解决方案：

在src目录执行./build/util/lastchange.py build/util/LASTCHANGE

3. gn gen out/ios --args='target_os="ios" target_cpu="arm64" is_debug=true'报错

Automatic code signing identity selection was enabled but could

not find exactly one code signing identity matching

iPhone Developer. Check that your keychain

is accessible and that there is a valid code signing identity

listed by xcrun security find-identity -v -p codesigning

TIP: Simulator builds don't require code signing...

解决方案：

1. 打开src/build/config/ios/ios_sdk.gni文件，把ios_code_signing_identity_description="iPhone Develoer"修改为ios_code_signing_identity_description="Apple Development"
2. 如果方法1不生效，可以尝试把命令更改为gn gen out/ios --args='target_os="ios" target_cpu="arm64" is_component_build=false ios_enable_code_signing=false' --ide=xcode

编译APP报错

/bin/sh: ../../third_party/llvm-build/Release+Asserts/bin/clang++: No such file or directory

解决方案：手动到官网https://commondatastorage.googleapis.com/chromium-browser-clang/index.html下载clang++，放到相应的文件夹(src/third_party/llvm-build/Release+Asserts)下面，注意clang++和macOS的版本对应问题

代码报错 set but not used [-Werror,-Wunused-but-set-variable]

variable 'zeroGainLvl' set but not used [-Werror,-Wunused-but-set-variable]

原因：这只是警告，只是clang++编译器将警告当作了错误输出

解决方案：

进入`build/config/compile/BUILD.gn`文件中，将`treat_warnings_as_errors`置为false