iOS-File-Watcher

This code is taken entirely from Daniel Galasko's public Medium post you can find here https://medium.com/over-engineering/monitoring-a-folder-for-changes-in-ios-dc3f8614f902

I just make his code into a Swift Package so that I didn't have to copy it into my projects. Better encapsulation that way 🎉

Only modification I made was changing some access levels from internal to public.

Also it seems like it would work for MacOS, tvOS and watchOS, but I haven't tested anything other than iOS.