iOS Background Task/Push Notification

Question

I am building an app that needs to speak data while the app is in the background (or screen is off). The speaking part is done via AVSpeechSynthesizer.

My Android app launches a service that listens for the data and whenever it needs to say something, I say it and its done. Now iOS doesn't allow these kind background tasks from what I read. The closet thing is called 'Executing Finite-Length Tasks' which looks like has a time limit of 10 mins max. So this will not work for me. Instead it looks like I need to use Push Notifications.

Looking at the documentation for Push Notifications, if I understand it correctly, if my app is in the Foreground, then my app receives the Push Notification instantly. While if my app is in the Background, a notification is set (notification center), and once the user hits the notification, my app launches with the payload.

The question here is, is there anyway to make a push notification wake my app immediately so I can speak some info?

Or what are some of the other alternative approaches that should be used in this case?

My other idea would be to implement some sort of mp3 stream per user, that would stream audio which I could play in the background. But this seems excessive for what I am trying to accomplish?

Answer 1

I'm not sure if you'll be able to invoke speech synthesis from the background, but you can have you app notified when the push arrives. The trick is to implement the

- (void) application: (RMApp *) application didReceiveRemoteNotification: (NSDictionary *) userInfo fetchCompletionHandler: (void (^)(UIBackgroundFetchResult result)) completionHandler

UIApplicationDelegate method (note the completionHandler parameter).

You must also set the Remote Notifications Background Mode capability.

And you must set content-available in your push notification payload.

A decent writeup on these steps found here:
http://samwize.com/2015/08/07/how-to-handle-remote-notification-with-background-mode-enabled/