override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    mBtnStartDownload.setOnClickListener {
        startUpdate()
    }

    register()
    //register2()
}

private fun startUpdate() {
    // 开启下载，下载会在IntentService中执行，如果当前正在下载中，不会重复执行下载任务
    DownloadManager.downloadApk(
        this, "https://XXX/YYY.apk"
    )
}

@SuppressLint("SetTextI18n")
private fun register() {
    DownloadManager.registerWithAutoInstall(this) { progress, speed ->
        mTvProgress.text = "${progress}%"
        mTvSpeed.text = speed
    }
}

// or auto manual install
@SuppressLint("SetTextI18n")
private fun register2() {
    DownloadManager.register(this, { progress, speed ->
        mTvProgress.text = "${progress}%"
        mTvSpeed.text = speed
    }, { fileName ->
        // there is a dialog in install method,if we register context is not activity,
        // we must manual install by this method.
        DownloadManager.installWithPermission(this, fileName)
    })
}

override fun onDestroy() {
    super.onDestroy()
    DownloadManager.unregister(this)
}