add google sign in for react native code example

Example 1: google login with react native

_signIn = async () => {
  try {
    await GoogleSignin.hasPlayServices();
    const {accessToken, idToken} = await GoogleSignin.signIn();
    setloggedIn(true);
  } catch (error) {
    if (error.code === statusCodes.SIGN_IN_CANCELLED) {
      // user cancelled the login flow
      alert('Cancel');
    } else if (error.code === statusCodes.IN_PROGRESS) {
      alert('Signin in progress');
      // operation (f.e. sign in) is in progress already
    } else if (error.code === statusCodes.PLAY_SERVICES_NOT_AVAILABLE) {
      alert('PLAY_SERVICES_NOT_AVAILABLE');
      // play services not available or outdated
    } else {
      // some other error happened
    }
  }
};

Example 2: google login with react native

return (
    <>
      <StatusBar barStyle="dark-content" />
      <SafeAreaView>
        <ScrollView
          contentInsetAdjustmentBehavior="automatic"
          style={styles.scrollView}>
          <Header />

          <View style={styles.body}>
            <View style={styles.sectionContainer}>
              <GoogleSigninButton
                style={{width: 192, height: 48}}
                size={GoogleSigninButton.Size.Wide}
                color={GoogleSigninButton.Color.Dark}
                onPress={this._signIn}
              />
            </View>
            <View style={styles.buttonContainer}>
              {!loggedIn && <Text>You are currently logged out</Text>}
              {loggedIn && (
                <Button
                  onPress={this.signOut}
                  title="LogOut"
                  color="red"></Button>
              )}
            </View>
          </View>
        </ScrollView>
      </SafeAreaView>
    </>
  );