OSErr - Any way of getting textual representation of error?

You might start by converting to an NSError, using NSError's +errorWithDomain:code:userInfo method. If you call -description on that error, you'll get a string with a textual representation of all the elements of the error.

However, I can't see any method that will give you just the underlying OSStatus error text, without the rest of the elements.

I hate to suggest parsing the string returned from -description, but that may be what you need to do.