お手軽な脈拍計測

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

        mSensorManager = getSystemService(Context.SENSOR_SERVICE) as SensorManager
        mHeartRate = mSensorManager.getDefaultSensor(Sensor.TYPE_HEART_RATE)
        mSensorManager.registerListener(this, mHeartRate, SensorManager.SENSOR_DELAY_NORMAL)

        for (permission in PERMISSIONS) {
            if (ContextCompat.checkSelfPermission(this, permission) != PackageManager.PERMISSION_GRANTED) {
                if(ActivityCompat.shouldShowRequestPermissionRationale(this, permission)) {
                    Toast.makeText(
                        this, getString(R.string.toast_requires_permission, permission),
                        Toast.LENGTH_SHORT
                    ).show()
                }else{
                    ActivityCompat.requestPermissions(this, PERMISSIONS, REQCODE_PERMISSIONS)
                }
            }
        }

    override fun onSensorChanged(p0: SensorEvent?) {
        if (p0 != null) {
            when(p0.sensor.type){
                Sensor.TYPE_HEART_RATE -> {
                    var rate = p0.values[0]
                    Log.d(TAG, rate.toString())
                }
            }
        }
    }