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Building library for iOS

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Dusko Ojdanic edited this page Aug 13, 2020 · 21 revisions

Rustup installation

  • Install rustup
  • Add device target: rustup target add aarch64-apple-ios,
  • Add simulator target: rustup target add x86_64-apple-ios
  • Proceed with scripted/manual flow

A) Scripted flow

  • Install rust-bitcode library (it will handle issues arising from iOS and Rust toolchain using different LLVM versions)
  • Set the path to your local copy of the iOS app's repo in the PATH_TO_IOS_REPO environment variable.
  • Execute the create_ios_universal.sh script. This will generate a universal static library with Bitcode support and place it in ./target. It will also overwrite the library in the iOS app's Carthage folder, allowing to update the dependency locally without creating new releases.

Note: The first time you execute create_ios_universal.sh it will take a while. Subsequent builds will run in a few seconds.

Creating a new release:

  • Run the make_framework.sh script to create a static framework with the generated library. Alternatively, you can download one of the released versions and replace the binary (CoEpiCore) and header(s) inside the folder.
  • Create a new Release in Github and attach the framework as binary.

NOTE: You have to attach the Android binaries as well. Instructions here.

B) Manual flow (alternative)

With Bitcode

Build for device

Xcode uses often a different LLVM version than Rust, which generates incompatible Bitcode. The rust-bitcode library helps us with this.

After you've installed this library, in this repo's root folder,

  • execute:
RUSTFLAGS="-Z embed-bitcode" cargo +ios-arm64 build --target aarch64-apple-ios --release --lib

This will generate the library for the device and save it in ./target/aarch64-apple-ios/release/

Build for simulator

The simulator doesn't require bitcode, independently of the project's settings. So you can create the library with only cargo build --target=x86_64-apple-ios

Create universal library with bitcode

We've now 2 separate libraries for the simulator and the device. We have to merge them into one, which can be used by Xcode. From the root directory of this repo, execute:

libtool -static -o libtcn_client.a ./target/aarch64-apple-ios/release/libtcn_client.a ./target/x86_64-apple-ios/release/libtcn_client.a

The generated libtcn_client.a will be where you indicate, in this case, in the same directory where libtool was executed.

Without Bitcode (not recommended)

  • Turn off Bitcode support in Xcode
  • Run in the root directory of this repo: cargo lipo --release. This generates a universal library for all supported architectures.
  • You will find the library in ./target/universal/release/

Creating and integrating static framework:

See scripted section.

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