Control push notification device registration - ios

Question

I am implementing the push notification service in my app. I created a the service on the Easy Apns style, but in a simpler way. I have a service that uses a MySql database to store the application tokens and a second service that accesses to the database, prepares the notifications and sends them.
It works, but I'm not sure if my registration part (on the client side) is correct.
The app delegate method:
- (void)application:(UIApplication*)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData*)deviceToken {
NSString *devToken = [[[[deviceToken description]
stringByReplacingOccurrencesOfString:#"<"withString:#""]
stringByReplacingOccurrencesOfString:#">" withString:#""]
stringByReplacingOccurrencesOfString: #" " withString: #""];
NSString *urlString = [#"/apns.php?"stringByAppendingString:#"task=register"];
urlString = [urlString stringByAppendingString:#"&appname="];
NSString *appName = [[[NSBundle mainBundle] infoDictionary] objectForKey:#"CFBundleDisplayName"];
urlString = [urlString stringByAppendingString:appName];
urlString = [urlString stringByAppendingString:#"&devicetoken="];
urlString = [urlString stringByAppendingString:devToken];
NSString *host = #"myservice.php";
NSURL *url = [[NSURL alloc] initWithScheme:#"http" host:host path:urlString];
NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url];
NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
}
This code updates the token each time the app is restarted. Is it correct? Shouldn't the registration phase happen just once (for example, the first time the user accepts the notification service)? In my case, every time the app is restarted, the token is added to my database (so I have to control from the server side if it is a replicated token).

Answer 1

There's nothing wrong in the way you are registering to APNS, but you can do it more efficiently.
Apple suggests that you register to the APN service every time the app is launched (and not only on the first time it is launched), because theoretically the device token might change (though it practice it almost never does).
An application should register every time it launches and give its provider the current token.
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 or computer other than the one that the backup was created for (for example, the user migrates data to a new device or computer), 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 computer, 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 the operating system passing the device token to the delegate immediately without incurring additional overhead.
You can store the device token locally in NSUserDefaults, and each time didRegisterForRemoteNotificationsWithDeviceToken is called, you can compare the newly received device token with the stored device token. You need to send the device token to your server only if it's different than the stored one. That would save unnecessary server calls.