lib/commands/file-movement.js
async function pushFileToSimulator (device, remotePath, base64Data) {
  const buffer = Buffer.from(base64Data, 'base64');
  if (CONTAINER_PATH_PATTERN.test(remotePath)) {
    const [bundleId, dstPath] = await parseContainerPath(remotePath,
      async (appBundle, containerType) => await getAppContainer(device.udid, appBundle, null, containerType));
    log.info(`Parsed bundle identifier '${bundleId}' from '${remotePath}'. ` +
      `Will put the data into '${dstPath}'`);
    if (!await fs.exists(path.dirname(dstPath))) {
      log.debug(`The destination folder '${path.dirname(dstPath)}' does not exist. Creating...`);
      await mkdirp(path.dirname(dstPath));
    }
    await fs.writeFile(dstPath, buffer);
    return;
  }
  const dstFolder = await tempDir.openDir();
  const dstPath = path.resolve(dstFolder, path.basename(remotePath));
  try {
    await fs.writeFile(dstPath, buffer);
    await addMedia(device.udid, dstPath);
  } finally {
    await fs.rimraf(dstFolder);
  }
}
async function pushFileToSimulator (device, remotePath, base64Data) {
  const buffer = Buffer.from(base64Data, 'base64');
  if (CONTAINER_PATH_PATTERN.test(remotePath)) {
    const [bundleId, dstPath] = await parseContainerPath(remotePath,
      async (appBundle, containerType) => await getAppContainer(device.udid, appBundle, null, containerType));
    log.info(`Parsed bundle identifier '${bundleId}' from '${remotePath}'. ` +
      `Will put the data into '${dstPath}'`);
    if (!await fs.exists(path.dirname(dstPath))) {
      log.debug(`The destination folder '${path.dirname(dstPath)}' does not exist. Creating...`);
      await mkdirp(path.dirname(dstPath));
    }
    await fs.writeFile(dstPath, buffer);
    return;
  }
  const dstFolder = await tempDir.openDir();
  const dstPath = path.resolve(dstFolder, path.basename(remotePath));
  try {
    await fs.writeFile(dstPath, buffer);
    await addMedia(device.udid, dstPath);
  } finally {
    await fs.rimraf(dstFolder);
  }
}
Save the given base64 data chunk as a binary file on the Simulator under test.

@param {Object} device - The device object, which represents the device under test.
This object is expected to have the `udid` property containing the
valid device ID.
@param {string} remotePath - The remote path on the device. This variable can be prefixed with
bundle id, so then the file will be uploaded to the corresponding
application container instead of the default media folder, for example
'@com.myapp.bla:data/RelativePathInContainer/111.png'. The '@' character at the
beginning of the argument is mandatory in such case. The colon at the end of bundle identifier
is optional and is used to distinguish the container type.
Possible values there are 'app', 'data', 'groups', '<A specific App Group container>'.
The default value is 'app'.
The relative folder path is ignored if the file is going to be uploaded
to the default media folder and only the file name is considered important.
@param {string} base64Data - Base-64 encoded content of the file to be uploaded.