Generating secure hash using iPhone Secure Enclave
You can simply create a database / enclave specific (symmetric) key and encrypt that using Enclave key pair. You can retrieve that wrapped key back by decrypting.

The password-derived key can simply be calculated like you do now.

So all that is left is to combine the keys back to one single key that depends on both. You could simply XOR the keys together for that. Or you could concatenate them and then use a KBKDF (which, in the simplest form, could just be a hash algorithm) to derive a new data key.

You could also concatenate the salt and the unwrapped key together and use that as salt input. Such a combination is called salt-and-pepper, where pepper is the secret part of the input. That way the derived key depends both on the secret and the password.

The derived data key can then be used to protect the database.



Don't forget to add authentication if you don't want the database to get corrupted by an attacker.