The AR session is attempting to resume after an interruption.
- iOS 11.3+
- Xcode 9.3+
ARKit cannot track device position or orientation when the session has been interrupted (for example, by dismissing the view hosting an AR session or switching to another app). When resuming the session after an interruption, the world coordinate system (used for placing anchors) likely no longer match the device's real-world environment.
If your session or view delegate implements the
session method and returns
true, ARKit attempts to reconcile pre- and post-interruption world tracking state. During this process, called relocalization, world tracking quality is
ARCamera, with a resaon value of
ARCamera, indicating that hit tests and anchor placement are less accurate.
If successful, relocalization ends after a short time, tracking quality returns to the
ARCamera state, and the world coordinate system and anchor positions reflect their state before the interruption.
For relocalization to succeed, the device must be returned to a position and orientation approximately near where it was when the session was interrupted. If these conditions never occur (or cannot occur; for example, if the device has moved to an entirely different environment), the session will remain in the
ARCamera state indefinitely.