Overview

Apple Push Notification Service (APNs) is Apple’s infrastructure for delivering remote notifications to iOS devices.

Unlike local notifications, remote notifications are sent from a server and delivered to devices through Apple’s servers.

Common uses include:

• chat messages
• breaking news alerts
• social media notifications
• order updates
• reminders triggered from a backend

Example use case:

A user sends a message in a chat app → the backend sends a push request to APNs → APNs delivers the notification to the recipient’s iPhone.

Remote Notification Flow

Remote notifications follow a different pipeline than local notifications.

App registers for remote notifications
        ↓
APNs generates device token
        ↓
App sends token to backend server
        ↓
Server sends push request to APNs
        ↓
APNs delivers notification to device

Important idea:

The server never sends pushes directly to the device.

All notifications must go through APNs.

Architecture