How to generate a bitcoin address from a hexadecimal private key using openssl in swift I have an iOS app which can generate Bitcoin private keys in either a hexadecimal or base64 output.  I'd like take the resulting private key and generate the Bitcoin address from it.  I've included the openssl library in my project but am confused as to which methods I should use and how to reference opaque pointers that come along with openssL methods when using them in swift.
I wanted to put this as a short comment, but it get’s unreadable. I also don’t go into segwit.
I am not clear on your question: are you looking how to use the OpenSSL library for iOS (then this might not be the right forum - review of parameters to an OpenSSL library is not bitcoin specific...), or more at the conceptual steps to come to an address? Then read on:-)
Searching for OpenSSL and keys in the forum reveals lots of hints on how to use OpenSSL at the command line. I put here some links, that I find useful for creation and conversion of keys:
Bitcoin Address generation
What are steps 4-9 in bitcoin address generation for?
Then you‘ll have to go some additional steps, as described in bitcoin wiki.
And finally, if you want to check the addresses, this is a useful page:
http://gobittest.appspot.com/Address
Let us know how it goes, and see where we can bring you to your goal!