[bryanl]

Isn't this what analytic packages are for? The app receiving the push message on your phone could anonymously provide analytics back to the server and with that knowledge alone, they know you are using it. Also additional analytics can be provided to see if you actually open the app.

[yoda_sl]

On iOS unless the receiving app is either an official background app (aka GPS/VOIP/Music) or if the app is in the foreground then you are out of luck the app will not know a push was received. The only time the app knows a push was received is when the user act on the notification or if the push did contain a badge then the app can access the badge value... Otherwise nope!

Basically the summary for iOS is really the push is received by the notification center -own by Apple, and your app has no access to it when it run. Technically too if you go in the iOS settings and decide to remove the app from the Notification Center screen, then the pushes start to be 'lost'.

The concept of push is good and iOS now are better than in the past but they are far from being perfect and the iOS settings screen is a mess/confusion when you start playing with it.