[toomuchtodo]

Push notifications are more efficient, as iOS manages the persistent connection to receive push notifications versus your application long polling.

https://news.ycombinator.com/item?id=9901686 (HN thread where Rob @ FastMail dives in depth why push notifications are superior to IMAP IDLE)

https://stackoverflow.com/questions/17262511/how-do-ios-push... (How do iOS Push Notifications work?)