PushSharp
A server-side library for sending Push Notifications to iOS
...PushSharp v3.0+ is a complete rewrite of the original library, aimed at taking advantage of things like async/await, HttpClient, and generally a better infrastructure using lessons learned from the old code. PushSharp will now follow semver versioning, so major version numbers will go up as there are any breaking API changes. The API in v3.x+ series is quite different from 2.x. The goal is to simplify things and focus on the core functionality of the library, leaving things like constructing valid payloads up to the developer. For APNS you will also need to occasionally check with the feedback service to see if there are any expired device tokens you should no longer send notifications to.