Google Developers, on surprisingly-it's-still-around Google Plus:
Getting your app content found on Google just got easier. App Indexing is now compatible with HTTP deep link standards for iOS 9, as it has been on Android from the beginning. That means that you can start getting your app content into the Search results page on Safari in iOS, simply by adding Universal Links to your iOS app, then integrating with our SDK. With this improvement, we will no longer support new integrations on iOS 7 and iOS 8. Users will start seeing your app content in Safari on iOS at the end of October.
Google has additional documentation here. I'm glad they're adding support for this relatively soon.