Verify that network request was sent by iOS application

Verify that network request was sent by iOS application

I'm trying to verify that HTTP requests from iOS application were really
sent from mobile application. Currently server code just checking
'User-Agent' HTTP header and of course it's not very reliable solution.
Here is how I see current iOS SDK can be used to verify that client is an
actual iPhone user.
Push notifications
iOS app requests push token from the operating system and sends it to server
Server sends push notification to application with hidden identifier
iOS app sends received identifier to server
Server responds with cookie
Here on the first stages of communication we can verify that user is
mobile user because how else she got identifier from push notification to
specific app.
dis. Not quite reliable even if we can repeat push notification. Misuse of
push notifications.
In-App purchase
It is possible to reuse receipt verification here.
dis. Obvious misuse. Confusing.



So the question is – are there any proper ways to confirm that request was
sent from iOS application, from iOS device ?