I have an App which allows the user to send images to other users. It is available for Windows (x86), iOS (tablet and phone), Android (iPhone and iPad) and Windows Phone. Now, if a user is working on a Windows PC and his Smartphone is lying next to him, he gets a notification on both devices, this is could become very annoying.
Are there any known solutions how to "synchronize notifications" on multiple devices? (Only one notification is shown on the used device)
For example skype has solved this problem with his so called "active endpoints"-feature. Does anyone know how they could have implemented this?
Essentially, this feature is totally built-in to PubNub - indeed it's the raison d'etre of PubNub.
http://www.pubnub.com/blog/five-ways-you-can-use-pubnub-presence/
"Presence detects when users enter or leave your app, and gives the online/offline status of machines and devices connected to your app..."
Maybe you need to ask a more detailed question - "Can I do 'active endpoints feature' with PubNub?" - either here or on the PubNub forum.
Note that if you're using Parse, that is basically now back4app.com.