Create informational popup / tooltip in Cocoa

Question

The question title is kind of vague, but I really don\'t know what the thing is called.

I am trying to

Answer 1

If you are using NSTextView, you can even set an attribute for a certain range in NSTextstorage, that displays the Tooltip. Something like:

[textStorage addAttribute:NSToolTipAttributeName
                    value:error.description
                    range:range];

Answer 2

That's called a tool tip. You can set the tool tip for any NSView using setToolTip:.