iOS push services: is an invisible push notification possible?

Question

I\'m building a iPhone application which depends data from an online database.

To update the data in the app i could check at a certain time interval if an update is ne

Answer 1

Use the delegate methods applicationDidRecieveRemoteNotification to tell the app to check in with the update service. Or you can have the app poll the update service durin applicationwillEnterForgound of you don't want to set up push notifications.

Answer 2

Yes, it is possible with iOS 7+

You can receive "background" push notifications if you override this method of UIApplicationDelegate: application(_:didReceiveRemoteNotification:fetchCompletionHandler:)

func application(application: UIApplication, didReceiveRemoteNotification userInfo: [NSObject : AnyObject], fetchCompletionHandler completionHandler: (UIBackgroundFetchResult) -> Void)
{
    // do what you need i.e. download fresh content (max. 30 seconds)

    completionHandler(UIBackgroundFetchResult.NoData)
}

As documentation of this method method says:

Use this method to process incoming remote notifications for your app. Unlike the application:didReceiveRemoteNotification: method, which is called only when your app is running in the foreground, the system calls this method when your app is running in the foreground or background. In addition, if you enabled the remote notifications background mode, the system launches your app (or wakes it from the suspended state) and puts it in the background state when a remote notification arrives.

Don't forget to enable "Background fetch" and "Remote notifications" in your background modes.

More info about background execution here.

Answer 3

Short answer to your first question: You have to poll.

Why :- When your app is in the background, it can not know of any push notifications, unless there is an alert and user clicks View or Launch, which is not guaranteed (and you don't want the alert too).

You may also want to avoid using APNS (if its only for this purpose), because of the additional overhead of configuring a server with Apple certificates and all that jazz.

To answer to your second question: How frequent you want your updates really depends on what your app does. For example, if you are showing "Stock" values, you may want to update the data every few seconds. For weather, it may be a few hours. For others, it may be days or even longer. It depends on how critical the updates are for the user.

Answer 4

You cannot send an invisible push notification while the application is in background. The only way is to update the data when the application comes to the foreground.

You would check at a certain time interval if an update is necessary or make a pull connection with the server.

Answer 5

You can receive notification while you are in foreground, but the server won't make any difference if you are in background or in foreground, unless you send an information to the server that you are in foreground.

That's why in your case, ase described in the previous message, it's better to check with the server when you came from background or when the application starts if there is any upload.

The other option is to send a visible notification so the user will start the application and then the update (as described in the previous paragraph) will happens

Answer 6

I dont' think your is the right approach. Consider all the stuff You will build for a simple task: 1) server for push 2) registering for notification 3) going background and resuming (the big and complicated is the server for push notification)

and anyway when You got a message, you must ask the data... no savings comparing asking directly.

So a clean solution can be: 1) ask to the server using normal HTTP (using async NSURL request..) for example: http://...... &lastupdate='2012:05:01 18 00' passing the last update date we got a successful download (You can also use a unicx time stamp...)

2) the server will compare that date with its internal last update date: if it has newer date, it will respond with XML or plist (i prefer plist...)

3) the app downloads new data and updates the date/time.

4) if no data the answer is simply an empty string or for example the same date we sent.