How to use the react-native-vector-icons/MaterialCommunityIcons.getImageSource function in react-native-vector-icons

componentDidMount() {
        if(!isIOS) {
            MaterialIcons.getImageSource('qrcode-scan', 26, '#FFFFFF').then(icon => {
                this.props.navigator.setButtons(
                    {
                        fab: {
                            collapsedId: 'scan',
                            collapsedIcon: icon,
                            collapsedIconColor: colors.white,
                            backgroundColor: colors.brand
                        },
                    }
                )
            })
        }
    }

componentDidMount() {
    if (!isIOS) {
      MaterialIcons.getImageSource('qrcode-scan', 26, '#FFFFFF').then(icon => {
        this.props.navigator.setButtons({
          fab: {
            collapsedId: 'scan',
            collapsedIcon: icon,
            collapsedIconColor: colors.white,
            backgroundColor: colors.brand,
          },
        })
      })
    }
  }

componentDidMount() {
    if (Device.isAndroid) {
      MaterialIcons.getImageSource('qrcode-scan', 26, '#FFFFFF').then(icon => {
        this.props.navigator.setButtons({
          fab: {
            collapsedId: 'scan',
            collapsedIcon: icon,
            collapsedIconColor: Theme.colors.primary.background,
            backgroundColor: Theme.colors.primary.brand,
          },
        })
      })
    }
  }

taxiTypes.forEach(type => {
      Icon.getImageSource(type.icon, 25, "orangered").then(image =>
        this.setState({ ...this.state, [type.type]: image })
      )
    })
  }