constructor(props) {
    super(props);

    setInterval(() => {
      this.setState(previousState => {
        return { isShowingLine: !previousState.isShowingLine };
      });
    }, 600);
  }

  state = {
    data: ['', '', '', '', '', ''],
    value: '',
    status: [true, false, false, false, false, false],
    isShowingLine: true
  }

  componentWillUnmount() {
    this.timer && clearTimeout(this.timer);
  }

  render() {
    return (
      <View style={styles.container}>
        <View style={styles.textInputContainer}>
          {
            this.state.data.map((item, index) => {
              return (
                <View key={index} style={styles.item}>
                  {
                    !this.state.status[index] ?
                      <Text key={index + 1000} style={styles.txt}>{item}</Text> :
                      this.state.isShowingLine ?
                        <View style={styles.line}></View> :
                        <View></View>
                  }
                </View>
              )
            })
          }
        </View>
        <TextInput
          ref={ref => { this.textInput = ref }}
          underlineColorAndroid="transparent"
          style={[styles.textInput, { marginTop: -45 }]}
          autoFocus={true}
          keyboardType={'number-pad'}
          maxLength={6}
          selectionColor={'transparent'}
          value={this.state.value}
          onChangeText={(text) => {
            this.onChangeText(text)
          }}
        />
      </View>
    );
  }

  onChangeText = (text) => {
    var s = []
    for (let index = 0; index < 6; index++) {
      if (index == text.length) {
        s.push(true)
      } else {
        s.push(false)
      }
    }

    var str = text + '      '
    this.setState({
      data: str.split('', 6),
      value: text,
      status: s
    })

    if (text.length == 6) {
      Keyboard.dismiss()
      this.timer = setTimeout(() => {
        this.setState({
          data: ['', '', '', '', '', ''],
          value: '',
          status: [true, false, false, false, false, false],
          isShowingLine: true
        })
        this.textInput.focus()
      }, 5000)
    }
  }


const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#F5FCFF',
  },
  textInputContainer: {
    flexDirection: 'row',
    paddingHorizontal: 30,
    width: width,
    justifyContent: 'space-around',
  },
  textInput: {
    color: 'transparent',
    backgroundColor: 'transparent'
  },
  item: {
    width: 45,
    height: 45,
    borderBottomWidth: 1,
    borderBottomColor: 'red',
    justifyContent: 'center',
    alignItems: 'center'
  },
  txt: {
    flex: 1,
    fontSize: 36,
    fontWeight: '700',
    textAlign: 'center'
  },
  line: {
    backgroundColor: 'red',
    width: 1.5,
    height: 30
  }
});

test.png