React Native Stream Group Chat Tutorial: render login screen UI

render UI in Login.js

// src/screens/Login.js
render() {
  const { username, is_loading } = this.state;
  return (
    <View style={styles.wrapper}>
      <View style={styles.container}>

        <View style={styles.main}>
          <View style={styles.field_container}>
            <Text style={styles.label}>Enter your username</Text>
            <TextInput
              style={styles.text_input}
              onChangeText={username => this.setState({ username })}
              value={username}
            />
          </View>

          {!is_loading && (
            <Button title="Login" color="#0064e1" onPress={this.login} />
          )}

          {is_loading && (
            <Text style={styles.loading_text}>Loading...</Text>
          )}
        </View>
      </View>
    </View>
  );
}