How to Build for iOS Targets When Using Rust (via uniffi)

[AndreasLarssons]

We’re currently building an SDK using Rust with uniffi to expose wallet functionality and shared business logic across platforms. We want to utilize wallet-core as the crypto layer, together with other functions like API requests and database management.

We’ve been able to import the wallet-core Rust crate successfully, following the guidance in this discussion.

However, we now want to use more of the higher-level APIs — for instance, HDWallet and related functionality. When we follow the samples/rust approach and target our host platform (macOS), everything works as expected.

The issue arises when we attempt to build for a different architecture, such as:

cargo build --target aarch64-apple-ios --release

At this point, the linker throws errors about missing symbols or mismatched architectures. Based on our understanding, the root cause is likely that the .a files in the /build/ directory (like libTrustWalletCore.a or libTrezorCrypto.a) are built for the host architecture only by default.

Question:
Is there a supported way to generate the /build/ artifacts for a specific target architecture (e.g., aarch64-apple-ios) so we can use them in a Rust project targeting iOS via cargo build --target?

Any insight into a correct CMake invocation or cross-compilation strategy that produces the right .a files for non-host targets would be greatly appreciated.

Thanks in advance!

[satoshiotomakan]

Hi @AndreasLarssons, currently, we use build runners with the architecture for which we need to build the project. Currently, we only have wasm-emscripten as a cross-platform target you can build on MacOS or Linux.
There was a PR to add support for universal build but only for MacOS platform, and we decided to not include for now - https://github.com/trustwallet/wallet-core/pull/4090/files

Unfortunately, we don't have plan to add support for cross-platform compilation of the C++ codebase, but hope the PR I mentioned above will help with this.

Please let me know if you have any other questions

[AndreasLarssons]

Heya! Thanks for the detailed answer.

Is it possible to utilize the same strategy as your build runners to create those binaries? Could you explain a bit more how the build runners are setup? Potentially that would be something we could replicate in that case.