We have an app that has a deployment target of iOS 13.0 and was built using Xcode 13.2.1.
An embedded custom framework implements an iOS 14 widget, has a deployment target of iOS 14, and weak links against WidgetKit and SwiftUI.
When running on iOS 13.0-13.3.x we are getting a crash on launch:
Symbol not found: _swift_getTypeByMangledNameInContextInMetadataState\n Referenced from: /private/var/containers/Bundle/Application/AA26538A-91B0-4B27-BA5D-0C0CEA30CEED/X.app/Frameworks/WidgetUI.framework/WidgetUI (which was built for iOS 14.0)\n Expected in: /usr/lib/swift/libswiftCore.dylib\n
(BTW it took some work to get this message. dyld's ImageLoaderMachO::throwSymbolNotFound results in a failed_throw which terminates the app without any messages. So I had to create a symbolic breakpoint for ImageLoaderMachO::throwSymbolNotFound and step thru the assembly in lldb as the exception string was getting built)
On iOS 13.4.x-13.7, we don't see a crash which appears to be because swift_getTypeByMangledNameInContextInMetadataState got introduced in iOS 13.4.
Looking at nm -a on the iOS 14.0 framework it appears that linking against SwiftUI is what's causing the framework to reference _swift_getTypeByMangledNameInContextInMetadataState
The custom framework is not marked as optional in our production code, but changing it to optional doesn't fix the crash.
Anything else we could try to avoid this crash?
side note: When I run otool -L on the framework all the swift libraries have a prefix of /usr/lib/swift. For example /usr/lib/swift/libswiftCore.dylib Is this correct?