Bug Report userState React Hooks

Expected Behavior

When using “const [devices, setDevices] = useState([])” or any statefunction inside the scaning from ‘startDeviceScan’ the event stops

Current Behavior

The event stop and no more devices are found

Context

[CoreBluetooth] API MISUSE: <CBCentralManager: 0x281ab8af0> has no restore identifier but the delegate implements the centralManager:willRestoreState: method. Restoring will not be supported 2020-01-19 20:06:06.293648+0100 Zipforce[23222:18432691] [CoreBluetooth] XPC connection invalid [RxBLEKit|DEBG|19:06:06.301]: CentralManager(10765437680) didUpdateState(state: poweredOn)

• Library version: 1.1.1
• Platform: OS.
• Platform logs (XCode):

const bleManager = new BleManager();

    const [deviceScan, setDeviceScan] = useState(false)
    const [devices, setDevices] = useState([])

    const stopDeviceScan = () => {
        console.trace('stopDeviceScan')
        bleManager.stopDeviceScan()
        setDeviceScan(false)
    }

    const addDevice = (device) => {
        console.trace('addDevice')
        console.log(device.id, device.name, device.localName)
        if (device.isConnectable &&
            device.localName &&
            devices.findIndex((x) => x.id == device.id) === -1) {

            setDevices([...devices, {
                id: device.id,
                name: device.name,
                localName: device.localName,
                isConnectable: device.isConnectable,
                rssi: device.rssi
            }])
        }
    }

    const startDeviceScan = () => {
        console.trace('startDeviceScan')
        bleManager.startDeviceScan(null, { allowDuplicates: false }, (error, device) => {
            if (error) {
                console.error(error)
            } else {
                addDevice(device)
            }
        })
    }

    useEffect(() => {
        console.trace('Init - Timer')
        let timerId = setTimeout(() => {
            stopDeviceScan()
        }, 15000)
        return () => clearTimeout(timerId);
    }, [])

    useEffect(() => {
        console.trace('Init')
        setDevices([])
        setDeviceScan(true)
        const subscription = bleManager.onStateChange((state) => {
            switch (state) {
                case 'PoweredOn':
                    console.trace('PoweredOn')
                    subscription.remove();
                    startDeviceScan()
                    break;

                default:
                    break;
            }
        })
    }, [])

    useEffect(() =>{
        console.log('useEffect',devices)
    },[devices])

[dbloembe]

@Cierpliwy Could you explain why the BleManager cannot be instantiated inside the component?

Also, it would be extremely helpful to have an example react-native-ble-plx implementation using functional components. Do you know if this exists?

[zachandblue]

I’ve noticed the same thing when using monitorCharacteristicForService(). If I try to update state inside of my listener function, it only runs once and then stops.