1# WebRTC iOS development
2
3## Development Environment
4
5In case you need to build the framework manually
6(for instance if you need to support bitcode) or you want to try out the demo application
7AppRTCMobile, follow the instructions illustrated bellow.
8
9A macOS machine is required for iOS development. While it's possible to
10develop purely from the command line with text editors, it's easiest to use
11Xcode. Both methods will be illustrated here.
12
13_NOTICE:_ You will need to install [Chromium depot_tools][webrtc-prerequisite-sw].
14
15## Getting the Code
16
17Create a working directory, enter it, and run:
18
19```
20$ fetch --nohooks webrtc_ios
21$ gclient sync
22```
23
24This will fetch a regular WebRTC checkout with the iOS-specific parts
25added. Notice the size is quite large: about 6GB. The same checkout can be used
26for both Mac and iOS development, since GN allows you to generate your
27[Ninja][ninja] project files in different directories for each build config.
28
29You may want to disable Spotlight indexing for the checkout to speed up
30file operations.
31
32Note that the git repository root is in `src`.
33
34From here you can check out a new local branch with:
35
36```
37$ git new-branch <branch name>
38```
39
40See [Development][webrtc-development] for generic instructions on how
41to update the code in your checkout.
42
43
44## Generating project files
45
46[GN][gn] is used to generate [Ninja][ninja] project files. In order to configure
47[GN][gn] to generate build files for iOS certain variables need to be set.
48Those variables can be edited for the various build configurations as needed.
49
50The variables you should care about are the following:
51
52* `target_os`:
53  - To build for iOS this should be set as `target_os="ios"` in your `gn args`.
54  The default is whatever OS you are running the script on, so this can be
55  omitted when generating build files for macOS.
56* `target_cpu`:
57  - For builds targeting iOS devices, this should be set to either `"arm"` or
58  `"arm64"`, depending on the architecture of the device. For builds to run in
59  the simulator, this should be set to `"x64"`.
60* `is_debug`:
61  - Debug builds are the default. When building for release, specify `false`.
62
63The component build is the default for Debug builds, which are also enabled by
64default unless `is_debug=false` is specified.
65
66The [GN][gn] command for generating build files is `gn gen <output folder>`.
67
68After you've generated your build files once, subsequent invocations of `gn gen`
69with the same output folder will use the same arguments as first supplied.
70To edit these at any time use `gn args <output folder>`. This will open up
71a file in `$EDITOR` where you can edit the arguments. When you've made
72changes and save the file, `gn` will regenerate your project files for you
73with the new arguments.
74
75### Examples
76
77```
78$ # debug build for 64-bit iOS
79$ gn gen out/ios_64 --args='target_os="ios" target_cpu="arm64"'
80
81$ # debug build for simulator
82$ gn gen out/ios_sim --args='target_os="ios" target_cpu="x64"'
83```
84
85## Compiling with ninja
86
87To compile, just run ninja on the appropriate target. For example:
88
89```
90$ ninja -C out/ios_64 AppRTCMobile
91```
92
93Replace `AppRTCMobile` in the command above with the target you
94are interested in.
95
96To see a list of available targets, run `gn ls out/<output folder>`.
97
98## Using Xcode
99
100Xcode is the default and preferred IDE to develop for the iOS platform.
101
102*Generating an Xcode project*
103
104To have GN generate Xcode project files, pass the argument `--ide=xcode`
105when running `gn gen`. This will result in a file named `all.xcworkspace`
106placed in your specified output directory.
107
108Example:
109
110```
111$ gn gen out/ios --args='target_os="ios" target_cpu="arm64"' --ide=xcode
112$ open -a Xcode.app out/ios/all.xcworkspace
113```
114
115*Compile and run with Xcode*
116
117Compiling with Xcode is not supported! What we do instead is compile using a
118script that runs ninja from Xcode. This is done with a custom _run script_
119action in the build phases of the generated project. This script will simply
120call ninja as you would when building from the command line.
121
122This gives us access to the usual deployment/debugging workflow iOS developers
123are used to in Xcode, without sacrificing the build speed of Ninja.
124
125## Running the tests
126
127There are several test targets in WebRTC. To run the tests, you must deploy the
128`.app` bundle to a device (see next section) and run them from there.
129To run a specific test or collection of tests, normally with gtest one would pass
130the `--gtest_filter` argument to the test binary when running. To do this when
131running the tests from Xcode, from the targets menu, select the test bundle
132and press _edit scheme..._ at the bottom of the target dropdown menu. From there
133click _Run_ in the sidebar and add `--gtest_filter` to the _Arguments passed on
134Launch_ list.
135
136If deploying to a device via the command line using [`ios-deploy`][ios-deploy],
137use the `-a` flag to pass arguments to the executable on launch.
138
139## Deploying to Device
140
141It's easiest to deploy to a device using Xcode. Other command line tools exist
142as well, e.g. [`ios-deploy`][ios-deploy].
143
144**NOTICE:** To deploy to an iOS device you must have a valid signing identity
145set up. You can verify this by running:
146
147```
148$ xcrun security find-identity -v -p codesigning
149```
150
151If you don't have a valid signing identity, you can still build for ARM,
152but you won't be able to deploy your code to an iOS device. To do this,
153add the flag `ios_enable_code_signing=false` to the `gn gen` args when you
154generate the build files.
155
156## Using WebRTC in your app
157
158To build WebRTC for use in a native iOS app, it's easiest to build
159`WebRTC.framework`. This can be done with ninja as follows, replacing `ios`
160with the actual location of your generated build files.
161
162```
163ninja -C out/ios framework_objc
164```
165
166This should result in a `.framework` bundle being generated in `out/ios`.
167This bundle can now be directly included in another app.
168
169If you need a FAT `.framework`, that is, a binary that contains code for
170multiple architectures, and will work both on device and in the simulator,
171a script is available [here][framework-script]
172
173To build the framework with bitcode support, pass the `--bitcode` flag to the script like so
174
175```
176$ python build_ios_libs.py --bitcode
177```
178The resulting framework can be found in out_ios_libs/.
179
180Please note that you can not ship the FAT framework binary with your app
181if you intend to distribute it through the app store.
182To solve this either remove "x86-64" from the list of architectures in
183the [build script][framework-script] or split the binary and recreate it without x86-64.
184For instructions on how to do this see [here][strip-arch].
185
186
187[cocoapods]: https://cocoapods.org/pods/GoogleWebRTC
188[webrtc-prerequisite-sw]: https://webrtc.googlesource.com/src/+/refs/heads/master/docs/native-code/development/prerequisite-sw/index.md
189[webrtc-development]: https://webrtc.googlesource.com/src/+/refs/heads/master/docs/native-code/development/index.md
190[framework-script]: https://chromium.googlesource.com/external/webrtc/+/master/tools_webrtc/ios/build_ios_libs.py
191[ninja]: https://ninja-build.org/
192[gn]: https://gn.googlesource.com/gn/+/master/README.md
193[ios-deploy]: https://github.com/phonegap/ios-deploy
194[strip-arch]: http://ikennd.ac/blog/2015/02/stripping-unwanted-architectures-from-dynamic-libraries-in-xcode/
195