Environment:
iPadOS 27 Beta (Developer Beta)
iPad with Bluetooth Classic (iAP2/ExternalAccessory) + BLE active session
App uses UIKit, WKWebView, scene-based lifecycle
Problem:
When the user invokes the new Siri AI by long-pressing the power button while our app is in the foreground with an active Bluetooth Classic session, we observe:
No scene lifecycle callbacks fire — no sceneWillResignActive, no sceneDidEnterBackground, nothing. We confirmed by logging every UISceneDelegate method.
Main thread / data processing threads are starved for ~2 seconds, causing a backlog of incoming Bluetooth data. Our real-time data processing latency jumps from ~105ms to over 2,300ms within 2 seconds of Siri activation.
CADisplayLink / requestAnimationFrame callbacks show a ~935ms gap coinciding with the Siri overlay appearance, then irregular intervals afterward.
The Bluetooth Classic transport (ExternalAccessory/iAP2) remains physically connected throughout — the issue is purely host-side processing starvation.
What we've ruled out:
BLE link degradation: firmware-side diagnostics confirm 100% data delivery, 0 lost packets during the incident
Memory pressure from our app: our process memory stays flat; system-available memory drops ~14 units externally
Questions:
Is the absence of sceneWillResignActive when Siri AI activates on iPadOS 27 intended behavior, or a beta bug?
The new UIApplication.systemPrefersReducedResourceUsage property (iPadOS 27 beta) — is this intended to signal system overlays like Siri consuming resources? Does the corresponding systemPrefersReducedResourceUsageDidChangeNotification fire when Siri activates?
Are there recommended patterns for apps with real-time Bluetooth data processing to maintain thread priority during system overlays? We currently use default QoS for our data processing dispatch queues.
The processing starvation causes the waveform display to degrade (appears as a connectivity issue to the clinician) even though the wireless link is healthy. We need either:
A notification that a system overlay is active, so we can adjust our UI accordingly
Guidance on maintaining processing priority during Siri AI activation
Any community insight on workarounds would be highly appreciated.
Thanks.
Topic:
Machine Learning & AI
SubTopic:
Apple Intelligence
Tags:
iPadOS
UIKit
IOBluetooth
Siri and Voice
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