I'm brand new to Swift and I'm struggling to figure out how I can call a function from the watchOS app in my iOS app. All I'm trying to do is have a button in the iOS app that makes the watch vibrate:
Call a function from WatchOS App in iOS App
You can't directly call a function like that. Both apps, WatchOS and iOS, are seperate from each other. You'd need to set up a Watch Connectivity Session, send a message from your iOS app and have the Watch app react to it by vibrating.