WHAT YOU WILL LEARN IN THIS CHAPTER
How to use the Apple Push Notification service
Generating a certificate request
Generating a development certificate
How to create an App ID
How to configure an App ID for push notification
Creating a provisioning profile
How to provision a device
How to deploy an iPhone application onto a device
Using a push notification provider application
One of the key limitations of the iPhone is its constraint on running applications in the background, which means that applications requiring a constant state of connectivity (such as social networking applications) will not be able to receive timely updates when the user switches to another application.
Chapter 21 discusses the new multi-tasking feature of iOS 4. While you now have the ability to run your application in the background, the types of applications that are allowed to do so are limited. Also, applications running in the background are not allowed to have any network connectivity.
To overcome this limitation, Apple released the Apple Push Notification service (APNs). The APNs enable your device to remain connected to Apple's push notification server (PNS). When you want to send a push notification to an application installed on the users" devices, you (the provider) can contact the APNs so that it can deliver a push message to the particular application installed on the intended device.
When your iPhone application uses the Apple Push Notification service, the ...