Just came across this question. I had to do a lot of searching around for this answer for my own use case. First off Widevine is not officially supported with AVPlayer since it's owned by google, so your only officially supported option is FairPlay.
If you have an apple dev account here's the place where all the FairPlay documentation is. There are some examples in here too.
https://developer.apple.com/streaming/fps/
also I found this article, which has a lot of helpful implementation info:
https://medium.com/@burak.oguz/ios-fairplay-drm-integration-with-different-use-cases-8aff3d4248dd
hope that helps
Topic:
Media Technologies
SubTopic:
Streaming
Tags: