I have built a WatchKit extension in Swift. All works beautifully in the simulator when running directly from xcode.
I have linked to the extension from my Titanium project, and everything builds without error, yet when running the "xcrun simctl launch booted" command to launch the watch, I get an infinite loading animation.
Upon digging through the logs I got many errors such as “Unable to start plugin” and "activePlugInForIdentifier: returned nil for application". I also stumbled upon a crash log which seems to point the finger more accurately:
Process: JAS Watch WatchKit Extension 
Dyld Error Message:
Library not loaded: @rpath/libswiftCore.dylib
Referenced from: /Users/USER/Library/Developer/CoreSimulator/Devices/4CEFE848-E6EB-41D2-8968-754C449E19A8/data/Containers/Bundle/Application/5B42A276-DD25-4288-82A4-C1C2CFBE527E/Just a Score.app/PlugIns/JAS Watch WatchKit Extension.appex/JAS Watch WatchKit Extension
Reason: image not found
It seems that “libswiftCore.dylib” is not getting included, a quick Google search will lead you to discover that there is a flag in a projects build settings called “Embedded Content Contains Swift Code”. This flag needs to be checked in order to run an objective-c project with embedded Swift content.
I’m sure this would be the case with any Swift extension and Titanium for reproduction. Hopefully this flag solves the issue.
Urgency in finding a solution to this would be greatly appreciated.