Update fragment ui from broadcast receiver in MvvM architecture and Kotlin

Eventually I found a clean and modern solution like I wanted. The trick is to wrap the BroadcastReceiver in a LiveData. By using this pattern you can observe the connection LiveDada directly from your fragment and update the ui. Of Course it is also possible (like sergiy tikhonov mentioned) to have a companion object in the base activity with a LiveData that is getting updated from the BroadcastReceiver and you can observe it from the fragment, but I didn't like this approach.

So it works like this:

Create an enum with the states of the network.

enum class NetworkAvailability {
    UNKNOWN,
    CONNECTED,
    DISCONNECTED
}

Create the class that extends the LiveData. I am using the singleton pattern because I don't want multiple instances. I create a BroadcastReceiver instance and I register/unregister it in onActive and onInactive methods of the LiveData.

class ConnectionStateLiveData(val context: Context) : LiveData<NetworkAvailability>() {

    companion object {
        private lateinit var instance: ConnectionStateLiveData

        fun get(context: Context): ConnectionStateLiveData {
            instance = if (::instance.isInitialized){
                instance
            }else{
                ConnectionStateLiveData(context)
            }
            return instance
        }
    }

    private val connectivityBroadcastReceiver = object : BroadcastReceiver() {
        override fun onReceive(p0: Context?, p1: Intent?) {
            val connectivityManager =
                context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
            val netInfo = connectivityManager.activeNetworkInfo

            value = if (netInfo != null && netInfo.isConnected) {
                NetworkAvailability.CONNECTED
            } else {
                NetworkAvailability.DISCONNECTED
            }
        }
    }

    override fun onActive() {
        super.onActive()
        value = NetworkAvailability.UNKNOWN
        val broadcastIntent = IntentFilter()
        broadcastIntent.addAction(ConnectivityManager.CONNECTIVITY_ACTION)
        context.registerReceiver(connectivityBroadcastReceiver, broadcastIntent)
    }

    override fun onInactive() {
        super.onInactive()
        context.unregisterReceiver(connectivityBroadcastReceiver)
    }
}

And finally I observe the LiveData in my fragment.

ConnectionStateLiveData.get(context).observe(viewLifecycleOwner, Observer {
                if (it == NetworkAvailability.CONNECTED) {
                    binding.noInternetTextView.visibility = View.GONE
                }
            })