Can't use camera on apple ipad, What am I doing wrong?

[chuidylan]

Code

import { BrowserQRCodeReader } from '@zxing/browser'

  data() {
    return {
      codeReader: null,
      selectedDeviceId: 
    }
  },
  mounted() {
    this.codeReader = new BrowserQRCodeReader()
    console.log('ZXing code reader initialized', this.codeReader)
    this.previewElem = document.querySelector('#video')
    BrowserQRCodeReader.listVideoInputDevices().then(res => {
      this.selectedDeviceId = res[0].deviceId
    })
  },
 start() {
    this.codeReader.decodeFromVideoDevice(this.selectedDeviceId, this.previewElem, fakeCallBackFunction)
 }

when click "Start Button" I got this error:

undefined is not an object (evaluating 'navigator.mediaDevices.getUserMedia') v-on handler (Promise/async

Please Help!