Swift "Could not find module 'X' for target" in CI

By Daniel Zoghalchali·Latchkey

A binary framework or XCFramework ships a Swift module compiled for some architectures but not the one the runner is building for (often arm64 iOS Simulator on Apple silicon), so the compiler cannot find a usable module slice.

What this error means

The Swift build fails with "Could not find module 'SomeKit' for target 'arm64-apple-ios-simulator'; found: x86_64-apple-ios-simulator" or similar architecture mismatch.

error: Could not find module 'SomeKit' for target 'arm64-apple-ios-simulator';
found: x86_64-apple-ios-simulator, x86_64

Common causes

The framework lacks an arm64 simulator slice

On Apple silicon runners the simulator target is arm64, but the dependency was only built for x86_64 simulator, so no matching module exists.

A fat framework instead of an XCFramework

A legacy universal framework cannot distinguish arm64 device from arm64 simulator; the proper fix is an XCFramework with both slices.

How to fix it

Use an XCFramework with the simulator slice

1. Rebuild the dependency as an XCFramework that includes ios-arm64-simulator.
2. Replace the fat framework with the XCFramework in the project.
3. Clean DerivedData and rebuild so the new module is picked up.

xcodebuild -create-xcframework \
  -framework device/SomeKit.framework \
  -framework simulator/SomeKit.framework \
  -output SomeKit.xcframework

Build for a matching simulator architecture

If you must keep an x86_64-only framework, run the simulator build under Rosetta or target an x86_64 simulator destination.

arch -x86_64 xcodebuild -scheme App \
  -destination 'platform=iOS Simulator,name=iPhone 16' build

How to prevent it

• Distribute binary dependencies as XCFrameworks with all needed slices.
• Build CI simulator targets with arm64 on Apple silicon runners.
• Verify a framework includes ios-arm64-simulator before relying on it.

Frequently asked questions

Related guides

References

• GitHub Actions documentation