bitcode-local-swift-package-issue

1. Given an iOS app with a watch app Xcode project.
2. The watch app has bitcode explicitly enabled with ENABLE_BITCODE=YES.
3. A local Swift package is used as a library in the watch app.
4. This leads to a bitcode warning saying that "all bitcode will be dropped because the package was built without bitcode" when building the app on simulator builds.

Link to Swift Forums post

✅ Resolved:

It turned out that the root cause was explicitly setting ENABLE_BITCODE=YES in the watchOS extension target. This applies bitcode to all builds whereas with the default setting, bitcode is only selectively applied by Xcode. So sticking to the default value solved the issue.

Actual result

Building the app on simulator builds gives the following bitcode warning in the Built target SampleWatchApp Extension: Link SampleWatchApp Extension (arm64) step:

ld: warning: all bitcode will be dropped because '/Users/username/Library/Developer/Xcode/DerivedData/SampleApp-egrqmpcsrjdhaxfjdiwqjeljghpq/Build/Products/Debug-watchsimulator/LocalSwiftPackage.o' was built without bitcode. You must rebuild it with bitcode enabled (Xcode setting ENABLE_BITCODE), obtain an updated library from the vendor, or disable bitcode for this target.

Expected result

The app builds without warnings on simulator builds (like on physical device builds) when a local swift package is used in the watch app.

Steps to reproduce with the sample project

1. Select the "SampleApp" scheme and an iPhone simulator as the run destination.

2. Build the app.
   --> This leads to the bitcode build warning.

3. Cross check: Select a physical device as the run destination. (Configure Signing & Capabilities for the targets, if needed.)
   --> The bitcode build warning does not occur.

Environment

• iOS 14.5
• watchOS 7.4
• Swift tools version 5.3
• Xcode 12.5.1 (12E507)