I have an Xcode workspace with an iOS framework target and an iOS SampleApp target that depends on and embeds the framework. The framework is closed-source and thus gets delivered in binary form to customers, in a release package alongside a copy of the sources for the entire SampleApp project, so that they can test it out with our app and see how the integration is done.
With this setup, during the development phase, I can open the workspace in Xcode and build the SampleApp target, and because it has an explicit dependency on the framework, Xcode immediately triggers a build of the framework first and then the app is built and linked correctly.
Now I want to leverage the new XCFramework format to distribute this framework to customers instead of using lipo'ed fat frameworks. I update my shell script that produces the release package to create an xcframework bundle at the end with all the various platforms supported, and also update the SampleApp project to depend on this xcframework instead of on the individual frameworks as it did before.
But here comes the problem with the updated SampleApp: After removing the dependency on the frameworks, the workspace setup described above doesn't work anymore, i.e. Xcode will no longer automatically build the framework target when the SampleApp target is built, because the explicit dependency link between the two is now broken.
My first attempt at solving this involved making the xcframework part of my regular development workflow as well. For this I added a run-script phase to the framework build target that generates a current-platform-only xcframework bundle and copies it to the place where the SampleApp expects to find it, and then added the framework target to the targets of the SampleApp build scheme, in order for the framework to be built when the SampleApp is built. Unfortunately this approach does not work because Xcode 12 always seems to build both targets in parallel, no matter what the 'Parallelize Build' setting is set to, and because of that the app will fail to build simply because the xcframework is not yet ready when it's processed by the build system, which is very early in the build phases of the SampleApp. So unless there's a way to force Xcode to honor the order in which the build targets are defined in the scheme, this approach is a no-go.
If this approach cannot work then I'd have to ship the xcframework with the SampleApp unmodified, and instruct customers wanting to run the app to manually remove the references to the universal frameworks and then add/drag the xcframework to it. This would work but it's ugly and does not seem user friendly enough to me.
I'm also considering a different approach whereby the release script programmatically modifies the SampleApp.xcodeproj to depend on the xcframework instead of on the universal frameworks, but that seems like it could be a very fragile thing to do, so would rather avoid it if there's a better way.
This scenario does not seem unique to me so I'd guess someone else must have faced this problem too. If so, how did you solve it?
So I ended up solving this by programmatically modifying the SampleApp's project file at release time to link and embed the xcframework bundle instead of the universal frameworks.
Initially tried to use the tool pbxproj but it didn't quite work, the initial fat framework removal phase was not succeeding.
Then I figured I could try and diff the project.pbxproj file after having manually replaced the frameworks with an xcframework, and turns out it takes only a few small edits to get there, so they can be done programmatically with a simple shell script like the following:
#!/bin/bash
PROJECT_FILE=SampleApp/SampleApp.xcodeproj/project.pbxproj
FRAMEWORK_NAME=MyFramework.framework
XCFRAMEWORK_NAME=MyFramework.xcframework
sed -i '' "s|FileType = wrapper.framework; path = ${FRAMEWORK_NAME}; sourceTree = BUILT_PRODUCTS_DIR;|FileType = wrapper.xcframework; path = ${XCFRAMEWORK_NAME}; sourceTree = \"<group>\";|" ${PROJECT_FILE}
sed -i '' "s|${FRAMEWORK_NAME}|${XCFRAMEWORK_NAME}|g" ${PROJECT_FILE}
There might be small differences in other project setups but mostly it boils down to that. Just beware that if the xcframework is meant to be placed somewhere other than in the project root then you need both a name and a path properties in the first sed command, e.g.:
name = "MyFramework.xcframework"; path = "relative/path/to/MyFramework.xcframework"