flutter_reactive_ble - 如何在订阅前检查设备是否已连接

Question

I'm using this plugin to try to develop an app that uses a Bluetooth module.

GitHub https://github.com/PhilipsHue/flutter_reactive_ble/

I'm trying to modify what the example included in the source code, so that onTap of the list of devices, would connect and subscribeToCharacteristic .

but, it seems that the connectToDevice() method is declared as a stream,

and putting "await" before the method call won't really fit my criteria (on a device connected, then subscribeToCharacteristic)

how do I achieve this?

what I currently have in device_list.dart

(device) => ListTile(
    title: Text(device.name),
    subtitle: Text("${device.id}\nRSSI: ${device.rssi}"),
    leading: const BluetoothIcon(),
    onTap: () async {
        widget.stopScan();
        await widget.deviceConn.connect(device.id);
        //call to subscribeToCharacteristic(characteristic);
    });

Answer 1

await only works in case the method returns a future. You should listen to the stream and when the stream emits a the connected state you execute the subscribe call. For example:

_ble.connectToDevice(id: deviceId).listen(
      (update) {
        if(update.connectionState == DeviceConnectionState.connected){
       // execute subscribe
        }
      },