react.jsx

...
  renderHeader() {
    return (
      <View>
        <Text>{`Header`}</Text>
      </View>
    )
  }
...
  render() {
    return (
      <FlatList ListHeaderComponent={() => this.renderHeader()}  />
    )
  }
...
  render() {
    return (
      <FlatList ListHeaderComponent={this.renderHeader}  />
    )
  }
...