Not sure from your post if you are asking about features in the Mobile SDK, that you would use from Swift or ObjC. But, if you are, then…
Currently you can both create a username and password, then log in, or use an existing username and password, then log in. The SDK has both of those functions in it.
Not sure what you mean by setup picture in the workflow.
Not sure what you mean by the ability to modify the text for each instruction step. Its an SDK.
If you are not talking about the Mobile SDK that would be used from a programming language, then this may not be the right forum category for your quesitons.