hunk.code_window:   2) I want to upload my own keystore!
   ```
   ### If you choose to build for iOS
   The first time you build the project You will be prompted for your Apple ID and password for your developer account, and your Apple Team ID. This is needed to manage certificates and provisioning profiles, so we can build and send off push notifications.
  
hunk.labels: keep keep add keep keep keep keep
hunk.after_edit: > **Note:** If you choose the first option and later decide to upload your own keystore, we currently offer an option to clear your current Android keystore from our build servers by running `exp build:android --clear-credentials.` **This is irreversible, so only run this command if you know what you are doing!** You can download a backup copy of the keystore by running `exp fetch:android:keystore`. If you do not have a local copy of your keystore , you will be unable to publish new versions of your app to the Play Store. Your only option would be to generate a new keystore and re-upload your application as a new application. You can learn more about how code signing and keystores work [in the Android documentation](https://developer.android.com/studio/publish/app-signing.html).
  
hunk.file_path: docs/versions/v18.0.0/guides/building-standalone-apps.md
hunk.type: add
file: /**
   * Copyright (c) 2015-present, Facebook, Inc.
   *
   * This source code is licensed under the MIT license found in the
   * LICENSE file in the root directory of this source tree.
   *
   * @format
   * @emails oncall+react_native
   */
  
  'use strict';
  
  const PlatformIOS = require('../Platform.ios');
  const PlatformAndroid = require('../Platform.android');
  
  describe('Platform', () => {
    describe('OS', () => {
      it('should have correct value', () => {
        expect(PlatformIOS.OS).toEqual('ios');
        expect(PlatformAndroid.OS).toEqual('android');
      });
    });
  
    describe('select', () => {
      it('should return platform specific value', () => {
        const obj = {ios: 'ios', android: 'android'};
        expect(PlatformIOS.select(obj)).toEqual(obj.ios);
        expect(PlatformAndroid.select(obj)).toEqual(obj.android);
      });
    });
  });
  