How do I launch an application on system startup? (Mac OSX, Cocoa)

Question

I have a program that runs only in the toolbar (w/ time/date, spotlight, etc.) and I want to put an item in the preferences to allow the user to select whether to start my a

Answer 1

You need to add the app to login items.

See System Startup Programing Topics: Customizing Login and Logout

Answer 2

There are some different solutions to that but Apple wants you to use the launchd(8).

Refer to this one (different section from the already mentioned documentation, since the topic starter asked for 'system startup', not 'when a user logs in') for some further information.