What does `ARWorldTrackingTechnique: resource constraints [33]` mean?

Question

YuFeng2026 OP

Created 2w

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We are building an ARKit application targeting iPhone Pro devices on iOS 26.4+. During testing, we consistently observe the following log message at a specific point in our AR session (approximately 90° into a walking arc around a vehicle):

ARWorldTrackingTechnique: resource constraints [33]

What specifically does resource constraint code [33] represent?

Is it a VIO constraint type, a sensor fusion budget limit, or something else entirely? How does it differ from code [1] (which appears to be a general CPU starvation signal for the ARKit sensor fusion thread)?

Is there a public API to detect or respond to this specific constraint condition, short of waiting for a full ARCamera.TrackingState downgrade?

Was this constraint type introduced or changed in iOS 26.4?

Answered by Vision Pro Engineer in 891536022

There isn't a public API for looking up individual VIO error codes. When you receive errors about resource constraints like this one, it usually means that the system is overloaded and dropping frames or sensor data, which can, for example, be caused by blocking the main thread or retaining frames.

Answer 1

Vision Pro Engineer OP

Apple

6d

Accepted Answer

There isn't a public API for looking up individual VIO error codes. When you receive errors about resource constraints like this one, it usually means that the system is overloaded and dropping frames or sensor data, which can, for example, be caused by blocking the main thread or retaining frames.