Blog post with some helpful notes on getting Handoff/Universal Links to work.

Doesn’t work in sim
Entering URL in address bar of Safari won’t work, which makes sense, needs to be clicked (also in web pages loaded in Safari?)
https://limitless-sierra-4673.herokuapp.com provides better validation than apple’s tool (check if uploading an IPA also checks entitlements and all domains)
~~was adding entitlements file to the bundle needed or not?~~ Nope
Native (iOS) to Web (Mac Safari) Handoff: User activities must be made current from viewDidAppear and invalidated from viewDidDisappear. Making them current from viewDidLoad (so presumably when the VC is not in the responder chain yet) does not work.
Web (Mac Safari) to Native (iOS) Handoff: broken on iOS 9.0.x. Test on iOS 8.x or iOS 9.1 beta.
App Search Deep Link documentation makes it seem like App Links/Twitter Cards are a viable alternative or Smart Banners, supposedly also to have Universal Links work. This is not the case and you won’t find out until you run the validation tool: “Universal Links are not supported on Facebook App Links/Twitter Cards. Please use Custom URL Schemas.”
(the docs do mention this, I think ?, but add nonetheless) The app site config file is only downloaded the first time after installing an app, so make sure to remove the app and re-install for testing changes to the config file

artsy / mobile