How device receives push notification? - iphone sdk

I want to ask you guys How device receives push noti开发者_开发技巧fication? Is our device continuously connected to apple's server?

Many Thanks,

Nav

Device does not remain connected. In fact the app might not even be running any more.

The mechanism is as follows:

1. Your application has to register for notifications.
2. When it registers you get a token, which you send to your server.
3. When you wish to send a push notification, your server connects to Apple server and sends a message to the previously registered token.

Simple :)

For more details see: http://developer.apple.com/library/ios/#documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/ApplePushService/ApplePushService.html#//apple_ref/doc/uid/TP40008194-CH100-SW9