How to get email (login name) of user in iOS?

I use custom screen with 'from' and 'to' email and textview fields to get feedback from users. So, is there any iOS api to auto fill 'fro开发者_如何学Gom' field?

I would be seriously surprised if there were as its potentially a big security hole - if not caught by apple it could be used to harvest email addresses.

You can however invoke the email app to do something for you, as described in this other question. Here, the user is in control of whether to send the email or not, so is not a security issue.