Wait for service to be bound using coroutines

Question

So I have a method that binds to the service.

fun bindService() {
        val intent = Intent(this, BluetoothService::class.java)
        bindService(intent, serviceConnection, Context.BIND_AUTO_CREATE)
    }

Inside onCreate method I use this code:

 bindService()
        launch {
            delay(500L)
            service = serviceConnection.serviceBinder?.getService() as BluetoothService
        }

Is there more elegant way to wait for the service to be bound than using delay()?

Answer 1

I wrote this just now, and haven't tried it, but hopefully something like it could work. The magic is in suspendCoroutine, which pauses the current coroutine and then gives you a continuation thingy you can use to resume it later. In our case we resume it when the onServiceConnected is called.

// helper class which holds data
class BoundService(
        private val context: Context,
        val name: ComponentName?, 
        val service: IBinder?, 
        val conn: ServiceConnection) {
    fun unbind() {
        context.unbindService(conn)
    }
}

// call within a coroutine to bind service, waiting for onServiceConnected
// before the coroutine resumes
suspend fun bindServiceAndWait(context: Context, intent: Intent, flags: Int) = suspendCoroutine<BoundService> { continuation ->


    val conn = object: ServiceConnection {
        override fun onServiceConnected(name: ComponentName?, service: IBinder?) {
            continuation.resume(BoundService(context, name, service, this))
        }
        override fun onServiceDisconnected(name: ComponentName?) {
            // ignore, not much we can do
        }

    }
    context.bindService(intent, conn, flags)
}

// just an example
suspend fun exampleUsage() {
    val bs = bindServiceAndWait(context, intent, Context.BIND_AUTO_CREATE)
    try {
        // ...do something with bs.service...
    } finally {
        bs.unbind()
    }
}