MainActivity.kt

class MainActivity : AppCompatActivity() {

    companion object {
        private const val PERMISSION_REQUEST_CODE = 20
    }

    private lateinit var binding: ActivityMainBinding
    private lateinit var layout: View

    override fun onCreate(savedInstanceState: Bundle?, persistentState: PersistableBundle?) {
        super.onCreate(savedInstanceState, persistentState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        layout = binding.root
        setContentView(layout)

        if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
            != PackageManager.PERMISSION_GRANTED
        ) {
            if (ActivityCompat.shouldShowRequestPermissionRationale(
                    this,
                    Manifest.permission.ACCESS_FINE_LOCATION
                )
            ) {
                ActivityCompat.requestPermissions(
                    this,
                    arrayOf(Manifest.permission.ACCESS_FINE_LOCATION),
                    PERMISSION_REQUEST_CODE
                )
            } else {
                ActivityCompat.requestPermissions(
                    this,
                    arrayOf(Manifest.permission.ACCESS_FINE_LOCATION),
                    PERMISSION_REQUEST_CODE
                )
            }
        }
    }

    override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<out String>,
        grantResults: IntArray
    ) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)

        when (requestCode) {
            PERMISSION_REQUEST_CODE -> {
                if (grantResults[0] != PackageManager.PERMISSION_GRANTED) {
                    // permission denied
                    layout.showSnackbar(
                        R.string.location_permission_required,
                        Snackbar.LENGTH_INDEFINITE
                    ) {
                        action(R.string.action_ok) {
                            // open Settings to grant location permission
                            val intent = Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS)
                            startActivity(intent)
                        }
                    }
                } else {
                    // permission granted
                }
            }
        }
    }
}