@eskimo Thanks for the prompt response. Is this called out in the documentation anywhere ? I think this is something which is definitely not obvious and needs an explicit call out.

Which bit? That the pointer returned only remains valid for the execution of the call

Personally I think we should remove these automatic pointer conversions from the language because they make it too easy to do the wrong thing. Totally agree! Yes better would be to move to Apple's CryptoKit but cannot as of now due to minimum iOS 13 support. I have reported on the feedback assistant. Problem ID: FB8804161