What is a UITextView's "purpose description"?

In Apple's iOS Human Interface Guidelines > iOS UI Element Usage Guidelines > Controls > Text Field, there is a marvelous screenshot of a UITextfield. As mentioned in the text, that particular UITextField is "shown here with a purpose description and placeholder text".

From the looks of it, the "Current Location" is the placeholder text and the "Name" is the "purpose description". I've been scouring the net for more than a day now, trying to find a way to render a UITextField like that - display a label-like text on the left and a placeholder text right next to it. The placeholder bit is of course more than easy to implement. I'm baff开发者_运维技巧led with the purpose description bit. Anyone have an idea how this would be implemented?

Try the leftView property. Throw a label in there.