It's was a great Lister sample code for work with iCloud on iOS/MacOS.
I hit the link https://developer.apple.com/library/prerelease/watchos/samplecode/Lister on Resources page of https://developer.apple.com/videos/play/wwdc2015/411/ and it returns 404 Not Found.
Where is the Lister now?
Looks like someone saved it at Github: https://github.com/RommelTJ/Lister
It's a great example if we can find it! It shows iOS, watchOS, and macOS syncing a list very nicely. I ran it awhile ago and it worked great. Now I'm looking at using CloudKit and it's gone... If you find it, please post here--I'll do the same.
