index.ios.js

/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 * @flow
 */

import React, { Component } from "react";
import { AppRegistry, StyleSheet, Text, View, Button } from "react-native";
import { LoginManager } from "react-native-fbsdk";

export default class FBSDKExample extends Component {
  state = {
    isLoggined: false
  };
  loginWithFB = () => {
    if (this.state.isLoggined) {
      LoginManager.logOut();
      this.setState({ isLoggined: false });
      return;
    }
    LoginManager.logInWithReadPermissions([
      "public_profile",
      "email",
      "user_friends"
    ]).then(result => {
      if (result.isCancelled) {
        // User cancelled to login with FB
      } else {
        this.setState({ isLoggined: true });
      }
    });
  };

  render() {
    return (
      <View style={styles.container}>
        <Text style={styles.welcome}>Welcome to React Native!</Text>
        <Text style={styles.instructions}>
          To get started, edit index.ios.js
        </Text>
        <Text style={styles.instructions}>
          Press Cmd+R to reload,{"\n"}
          Cmd+D or shake for dev menu
        </Text>
        <Button
          title={this.state.isLoggined ? "Logout" : "Login with FB"}
          onPress={this.loginWithFB}
        />
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: "center",
    alignItems: "center",
    backgroundColor: "#F5FCFF"
  },
  welcome: {
    fontSize: 20,
    textAlign: "center",
    margin: 10
  },
  instructions: {
    textAlign: "center",
    color: "#333333",
    marginBottom: 5
  }
});

AppRegistry.registerComponent("FBSDKExample", () => FBSDKExample);