viewController.appear

Intercepts UIViewController’s own appearance callback at load time, ahead of the app’s own implementation. One reading each time a screen finishes appearing.


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

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

CAPTURED                  ELAPSED  INSTRUMENT

launch 194429250700832282
2026-08-23T15:02:35.933Z  +0.0s    uikit.viewController.appear(screen)
└─ viewControllerClass  UINavigationController
2026-08-23T15:02:35.934Z  +0.0s    uikit.viewController.appear(screen)
└─ viewControllerClass  DeviceViewController
2026-08-23T15:02:38.981Z  +3.0s    uikit.viewController.appear(screen)
└─ viewControllerClass  UINavigationController
2026-08-23T15:02:38.982Z  +3.0s    uikit.viewController.appear(screen)
└─ viewControllerClass  DomainListViewController
2026-08-23T15:02:44.291Z  +8.4s    uikit.viewController.appear(screen)
└─ viewControllerClass  InstrumentListViewController
2026-08-23T15:02:47.833Z  +11.9s   uikit.viewController.appear(screen)
└─ viewControllerClass  InstrumentViewController
2026-08-23T15:02:49.735Z  +13.8s   uikit.viewController.appear(screen)
└─ viewControllerClass  AppearedViewController

Getting Started

SDK

CLI

Instruments

Reference

viewController.appear