iOS BLE BytesReceived errors but equivalent StringsReceived program doesn't

[werrindaleck]

BLE_iOS_ByteReceived_bug.aia (218.2 KB)

Attached .aia has the blocks and a bit more comments

I was trying to connect a bluetooth heartrate monitor ( smartwatch ) to iOS AppInventor companion (TestFlight version 2.78.4) by subscribing to the heartrate bluetooth service. Every block worked, except for when I got to BytesReceived. Merely adding the block ( even empty ) caused the periodic error in the companion app:
wrong number of arguments (1 for 3). Irritants: ()

At some point I tried replacing the RegisterForBytes with RegisterForStrings ( and correspondingly switched BytesReceived for StringsReceived ) and the entire bluetooth chain worked, proving the problem is the block itself.

The downside is that the output is the corresponding ASCII character and ( presumably ) goes no higher than 127bpm ( above 127 the character no longer shows in the label ), but this will mostly suffice for the project I have.

Help is not needed. I am mostly reporting a bug that meaningfully impacts bluetooth on iOS. Though I would like the option to go higher in case I ever need to.

[ewpatton]

I've looked at the sources and you are correct. The callback function is only passing the values, disregarding the service and characteristic UUIDs (hence the 1 of 3 error). I should have a fix shortly.

[ewpatton]

I've pushed a new version to TestFlight that includes the fix for the BLE BytesReceived event:

MIT App Inventor for iOS version 2.78.4 on TestFlight

Hello all, Version 2.78.4 is now available for testing on TestFlight. It contains the following changes from the version in the App Store: Add support for CheckedColor and UncheckedColor to the CheckBox component Fix an issue in the CircularProgress component Add titlecase block Add support for MakeFullPath block in File component Add multiselect support in ListView Fix an issue related to ImageSprite origin when using the OrientationSensor Make the text input in Notifier use black text on al…

[werrindaleck]

Thank you! I have just tested the new BytesReceived, and it works without any issues.

After testing a few times:
an already-broadcasting smartwatch, already set up as a bluetooth device in the settings.
a smartwatch ( already set up as a bluetooth device in the settings ) that started broadcasting after app started scanning.

Can confirm that:
BLE on
iOS 26.4.1
TestFlight AppInventor companion 2.78.4 build 3
has successfully and with perfect repeatability:

Scanned for and found a bluetooth device based on service UUID:
0000180D-0000-1000-8000-00805F9B34FB
( using ScanForService )

Connected to the device
( using .Connect with index )

Subscribed to the service and characteristic UUID ( bluetooth heart rate service ):
0000180D-0000-1000-8000-00805F9B34FB
00002A37-0000-1000-8000-00805F9B34FB
using RegisterForBytes

Received and displayed to a label:
correct ServiceUUID,
correct CharacteristicUUID,
the heart rate displayed on my watch ( even when it goes above 127 bpm )
using BytesReceived

All with no manual intervention of any kind on the user’s side, except for a one-time set up of the bluetooth device in the iOS settings.