app.state

Subscribes to UIKit’s app-lifecycle notifications. A reading each time the app moves to the foreground, the background, or resumes from one.


Delivery	stream, onChange
Mechanism	notification
Requires	iOS 17+, basset 0.1.1+

Real output from basset request get, captured against a running app:

CAPTURED                  ELAPSED  INSTRUMENT

launch 12909160989600416811
2026-08-23T14:52:16.394Z  +0.0s    lifecycle.app.state(appLifecycle)
└─ appState          foreground
2026-08-23T14:52:22.717Z  +6.3s    lifecycle.app.state(appLifecycle)
└─ appState          background
2026-08-23T14:52:30.937Z  +14.5s   lifecycle.app.state(appLifecycle)
└─ appState          foreground
2026-08-23T14:52:31.249Z  +14.9s   lifecycle.app.state(appLifecycle)
├─ appState          resumed
└─ totalNanoseconds  8531486500

Getting Started

SDK

CLI

Instruments

Reference