iphone device token : can it be stored on the iPhone?

Question

Hi,

I have to developp an app that uses Push Notification in a particular way, and I had a pretty tricky question : can the device token be stored locally in the app sandbox? Here's the why : this app should implement a notification system that allows the user to subscribe for some particular events only, from the iphone. So to do so, I need to send to my database the Device Token of the iPhone at any time when the app is running, and from what I get, the device token is only avaliable when the

- (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken

is called right? Or is there any way to retrieve this information later?

Thanks.

Answer 1

You should store it somewhere on the phone. NSUserDefaults is a decent place to do it since it's not a big piece of data and you can retrieve it easily afterwards. I would also recommend saving it on your server, and only updating it if the token changes.

Answer 2

The push notification programming guide however recommends you not to store the token locally:

"An application should register every time it launches and give its provider the current token. It calls registerForRemoteNotificationTypes: to kick off the registration process."

…

"By requesting the device token and passing it to the provider every time your application launches, you help to ensure that the provider has the current token for the device. If a user restores a backup to a device other than the one that the backup was created for (for example, the user migrates data to a new device), he or she must launch the application at least once for it to receive notifications again. If the user restores backup data to a new device or reinstalls the operating system, the device token changes. Moreover, never cache a device token and give that to your provider; always get the token from the system whenever you need it. If your application has previously registered, calling registerForRemoteNotificationTypes: results in iOS passing the device token to the delegate immediately without incurring additional overhead."