How did Apple implement the "To" field in the Messages app's compose view?

I want to implement a very similar functionality to what Apple did in the To: field in the开发者_如何学Python Messages app. Basically replicate the same behavior when picking up phone numbers to Send to. Is this whole field a table cell or a label(to:)+textfield+add contact button?

Assuming it is just a textfield, how did they manage to make the names behave as single entities (for example, if I add multiple receipients) in the text field then deleting them?

I have no problems bringing up the picker and inserting a single name, but I have no idea how they did it when more than one recipient is chosen. Also, how was that rounded blue frame done around every name?

Any small hints in the right direction I would really appreciate. I can pick it up from there!

thanks guys!

Check out TTPickerTextField from Three20 to see how such a field is done.