iPhone PushNotification Registering Multiple Times - iphone

Question

I am using PushNotification for my app. It Seems that the device token is generated each time the application is loaded. So in my server I have many duplicate device tokens.
Do I need to check the device token before adding it to database or am i doing some thing wrong with implementation in app?
Below the code Segment that I am using.
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
// launchOptions has the incoming notification if we're being launched after the user tapped "view"
NSLog( #"didFinishLaunchingWithOptions:%#", launchOptions );
// [self.viewController handleDidReceiveRemoteNotification:userInfo];
// other setup tasks here....
[[UIApplication sharedApplication]
registerForRemoteNotificationTypes:(UIRemoteNotificationTypeBadge |
UIRemoteNotificationTypeSound |
UIRemoteNotificationTypeAlert)];
// [self updateWithRemoteData]; // freshen your app!
// RESET THE BADGE COUNT
application.applicationIconBadgeNumber = 0;
// ...
// call the original applicationDidFinishLaunching method to handle the basic view setup tasks
[self applicationDidFinishLaunching:application];
return YES;
}
- (void)application:(UIApplication *)app
didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)devToken {
[self sendDeviceTokenToRemote:devToken]; // send the token to your server
}
Could someone help? How can I store unique device tokens in my server?
thanks,
Nikil

Answer 1

In most cases, this APNs token assigned to each device is unique and constant. You can view it as another kind of UDID. So once a device is registered in your server's database, you don't have to register it again.
(This is the tricky part) However, according to Apple's documentation, APNs token could change, let's say, if the device has been updated to a higher version of OS or has some of its hardware be replaced with a new one. However, this doesn't happen that often.
As for converting and storing this APNs token in your app and in your server, check this post, iPhone pushNotification DeviceToken - How to "decrypt"
Hope it helps.

Answer 2

Applications should re-register for push notifications at each startup as a best-practice recommended by Apple. (see the Apple Local and Push Notifications Programming Guide)
How you store the device id in your server-side domain is up to you. One example would be to have a column representing the last time a device registered. You would add a row if it is a new device id, or update a row with a new timestamp if the device id already exists.