Example usage of BundleDelegate

GameActivity.kt

class GameActivity : AppCompatActivity() {
    private var Bundle.score by BundleDelegate.Int("key_score")
    private var score = 0

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        savedInstanceState?.let { score = it.score }
    }

    override fun onSaveInstanceState(outState: Bundle) {
        super.onSaveInstanceState(outState)
        outState.score = score
    }
}