Q:

iOS: How to notify the appDelegate from a UIViewController

Simple question about how to pass information in my iOS application.
The appDelegate has a variable myVar.
I have a UIViewController with a View with a switcher. When the switcher switches, I need to set another value to myVar.
Since UIViewController is not supposed to know the interface of appDelegate, how can I notify it about the switch and update its variable ?
NB. If you are going to answer "just send a message", please let me know how to implement it as well, since it is not clear.
thanks

A:

http://developer.apple.com/library/ios/#documentation/StringsTextFonts/Conceptual/TextAndWebiPhoneOS/KeyboardManagement/KeyboardManagement.html#//apple_ref/doc/uid/TP40009542-CH5-SW1
Can you do similar to keyboard notifications ?  
Idea is to implement custom Switch which sends notifications to all registered listeners; register what ever object you think should receive notifications.

