How do I make a BLE connection in compose multiplateform App. using kable Library

[mukeshkibbcom]

I am using the Kable library for BLE scanning and connection in a Compose Multiplatform (KMP) app for Android and iOS. Scanning works perfectly in both platforms, but I am unable to establish a connection with the BLE device. What could be the possible reasons, and how can I fix this issue?

implementation("com.juul.kable:core:0.27.0")

import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import com.juul.kable.Peripheral
import com.juul.kable.Scanner
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.update
import kotlinx.coroutines.launch

class ScanningViewModel : ViewModel(){

    private val scanner = Scanner()

    private var connectedPeripheral: Peripheral? = null

    private val _devices = MutableStateFlow<List<BleDevice>>(emptyList()) // You can store the device names here
    val devices: StateFlow<List<BleDevice>> = _devices

    fun startScanning() {
        viewModelScope.launch {
            try {
                 // Start scanning and collect advertisements
                scanner.advertisements.collect { advertisement ->

                    val deviceName = advertisement.name ?: "Unknown Device"
                    val txPower = advertisement.txPower ?: 0
                    
                    val newDevice = BleDevice(
                        name = deviceName,
                        peripheralName = "",  // Use peripheral name
                        txPower = txPower,
                    )

                    _devices.update { currentList ->
                        if (newDevice !in currentList) {
                            currentList + newDevice // Add the new device if not already present
                        } else {
                            currentList // Keep the list unchanged if device already exists
                        }
                    }
                }
            } catch (e: Exception) {
                e.printStackTrace()
            }
        }
    }
}

data class BleDevice(
    val name: String,
    val peripheralName: String, 
    val txPower: Int?,
)

Note : Connect methos is available in Peripheral object.

Expecting : Peripheral object because it has connect method

I tried with all possible version of kable lib

[twyatt]

It looks like you're acquiring an Advertisement and storing it in your devices list, but when you want to connect to the peripheral, you need to create the Peripheral using the advertisement.

In newer versions of Kable, that would look something like:

val peripheral = Peripheral(advertisement) {
    // todo: configure peripheral
    // see https://github.com/JuulLabs/kable?tab=readme-ov-file#peripheral for more details
}

peripheral.connect()

In older versions, you can use scope.peripheral(advertisement) { .. }.