NSDocument-based app, open dialog with 'New Document' button on launch

Question

TextEdit and Pixelmator both open an open-file-dialog on launch that has a 'New Document' button in the bottom left corner.

Is there any particular code available to achieve the very same effect?

The reason I ask is that Pixelmator's way of going about it, the 'New Document' button included, is exactly the same as TextEdit, and I figure there must be some simple way to achieve this but I must be missing it.

Answer 1

Turns out you need to enable iCloud.