How would iOS reminder functionality be implemented?

Question

What is the recommended way to implement a reminder functionality, which would survive the app being in an inactive state, and would wake it up at a predetermined time?

Using NSTimer seems to be OK in the foreground, but the user should be able to set a reminder, close the app, and do something else.

How is this done?

Answer 1

Look into local notifications:

http://developer.apple.com/library/ios/#documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/Introduction/Introduction.html

http://developer.apple.com/library/ios/#documentation/iPhone/Reference/UILocalNotification_Class/Reference/Reference.html#//apple_ref/occ/cl/UILocalNotification