
We’ve just released version 5.7.3 of the Courier iOS SDK — a major update for teams using Courier Inbox to power in-app notifications on iOS.
This release improves performance, reliability, and gives you more flexibility to build the experience you want.
Stronger socket connection handling
Real-time delivery is now more reliable when switching between foreground and background — ideal for mobile apps with dynamic in-app messaging.
New threading model with CourierActor
All Courier.shared functionality now runs on a dedicated thread called CourierActor. This keeps SDK work off the main thread and improves performance across the board.
Fully rebuilt inbox datastore
We’ve rebuilt how messages and events are stored and managed — all now handled exclusively within the CourierActor. This ensures greater reliability and data accuracy.
Simplified listener events
Listening for inbox updates is easier than ever. The new onMessageEvent callback lets you respond to message-level events — giving you the tools to build custom UIs without added complexity.
More tests, more confidence
We added new unit and integration tests to back these updates and support future releases.

Broadcasts: send one-time messages to your users, right from Courier
Broadcasts lets you send a one-time message to a group of your users, now or on a schedule, without leaving Courier.

Build and launch a hosted preference center that looks great on web and mobile
Courier's redesigned Preferences Editor and hosted preference center let you build, preview, and launch a branded notification preference center with no frontend code, plus new bulk APIs to migrate preferences.

Experiments: A/B test your messages inside Journeys
Experiments bring A/B testing into Journeys. On any send node, run 2 to 10 message variants, split traffic by weight, and Courier buckets each recipient deterministically, keeping them in the same variant across sends. Compare sent, delivered, open, and click rates per variant, then promote the one you want, without leaving your journey or bolting on a separate testing tool.
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