websockets and real time updates in iOS

I'm learning express.js and socket.io for making real-time web applications. From what I can gather, socket.io (and websockets) are available in the browser. So it can listen for events emitted by the server.

For my use case, the client is an iOS app not the browser, and I intend to use express+socket as a real time api, pushing updates to the client. Since iOS doesn't have websockets, how do I go about doing that? How do people currently push updates to these devices?