FB18383742 - Installing watchOS companion app using Core Bluetooth for iOS app using ASK is broken on both platforms 🍏

Demo Xcode project with barebones iOS target using AccessorySetupKit + watchOS companion using Core Bluetooth

Setup

🛠️ Xcode 16.4 (16F6)
📱 iPhone 13 mini (iOS 18.0.1)
⌚️ Apple Watch Series 10 (watchOS 11.3.1)

Observations

• As AccessorySetupKit does not request "Core Bluetooth permissions", when a watchOS companion app is installed after having installed the iOS app, the toggle in the watch settings for Privacy & Security > Bluetooth is turned off and disabled
• After removing the iPhone associated with the Apple Watch, Bluetooth works as expected in the watchOS app
• Upon reinstalling the iOS app, there's a toggle for Bluetooth in the iOS ASK app's settings and the ASK picker cannot be presented 🤨
• From ASK Documentation:

AccessorySetupKit is available for iOS and iPadOS. The accessory’s Bluetooth permission doesn’t sync to a companion watchOS app.

• But this doesn't address not being able to use Core Bluetooth in a watch companion app at all 🥲

Reproducing the bug

• Install the iOS + watchOS apps
• Launch iOS app, tap "start scan", observe devices can be discovered (project is set up to find heart rate monitors)
• Launch watchOS, tap allow on Bluetooth permission pop-up
• watchOS app crashes 💥
• Meanwhile, in the iOS app, there should be a log entry for 💗 CBCentralManager state: poweredOff and the ASK picker is no longer able to discover any devices
• The state of the device permissions:

• Remove the iOS app
• Relaunch the watchOS app
• Notice the CBCentralManager state is unauthorized
• Remove and reinstall the watchOS app
• Tap allow on Bluetooth permission pop-up
• watchOS app does not crash and CBCentralManager state is poweredOn
• The state of the watch permissions:

• Note that at this time the iOS app is not installed, there is no way to remove Bluetooth permission for the watch app:

• Reinstall + launch the iOS app
• Notice a warning in the log:

[##### WARNING #####] App has companion watch app that maybe affected if using CoreBluetooth framework. Please read developer documentation for AccessorySetupKit.

• Notice a log entry for 💗 CBCentralManager state: poweredOn before tapping start scan
• Tap start scan and observe another log entry:

Failed to show picker due to: The operation couldn’t be completed. (ASErrorDomain error 550.)

• ASErrorDomain 550:

The picker can't be used because the app is in the background.

• Is this the expected error? 🤔
• The state of the iOS permissions:

• The iOS ASK app now has Core Bluetooth permission 😵‍💫

Following up with Apple

• This is a known bug that should be fixed in watchOS 26 when Bluetooth permissions for watch apps can be set independently of the iOS app.