How to play drm (widevine) content in ios?

I wish to know ho can i implement the widevine content protection in an ios application.
At present time I have the application working using the native ios player (AvPlayer).
As far I understand, I have to get the Widevine's CDM.
Is there any sdk?
Where ca I find documentation and/or example codes / tutorials?

Thank you very much for any help as it's hard to find informations about this.

Sergio