如何在Android FirebaseMessagingService中创建倒计时？

dependencies {
    implementation 'androidx.core:core-ktx:1.7.0'
}

class MyCountDownTimer(private val millisInFuture: Long, private val countDownInterval: Long) : CountDownTimer(millisInFuture, countDownInterval) {
    override fun onTick(millisUntilFinished: Long) {
        // 更新倒计时的UI展示
    }

    override fun onFinish() {
        // 倒计时结束的处理逻辑
    }
}

class MyFirebaseMessagingService : FirebaseMessagingService() {
    private var countDownTimer: MyCountDownTimer? = null

    override fun onMessageReceived(remoteMessage: RemoteMessage) {
        // 接收到消息时启动倒计时
        startCountDownTimer()
    }

    override fun onDeletedMessages() {
        // 删除消息时取消倒计时
        cancelCountDownTimer()
    }

    private fun startCountDownTimer() {
        countDownTimer = MyCountDownTimer(60000, 1000) // 倒计时60秒，每秒更新一次
        countDownTimer?.start()
    }

    private fun cancelCountDownTimer() {
        countDownTimer?.cancel()
    }
}